IARC
Working Group Reports
Volume 8

Helicobacter pylori Eradication as aStrategy for Preventing Gastric Cancer

This report represents the views and expert opinions of an
IARC Working Group that met in Lyon, France
4–6 December 2013

Published by the International Agency for Research on Cancer,
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IARC Library Cataloguing in Publication Data
Helicobacter pylori eradication as a strategy for preventing gastric cancer / IARC Helicobacter
pylori Working Group (2013: Lyon, France)(IARC Working Group Reports; 8)
1. Helicobacter infections – epidemiology 2. Helicobacter infections – prevention andcontrol 3. Helicobacter infections – therapy 4. Helicobacter pylori 5. Stomach
neoplasms – prevention and control 6. Stomach neoplasms – microbiology 7. Stomach
neoplasms – epidemiology
I. IARC Working Group Report II. SeriesISBN 978-92-832-2454-9(NLM Classification: WI 320)

In publications, this report should be referred to as:
IARC Helicobacter pylori Working Group (2014). Helicobacter pylori Eradication as a Strategy
for Preventing Gastric Cancer. Lyon, France: International Agency for Research on Cancer(IARC Working Group Reports, No. 8). Available from: http://www.iarc.fr/en/publications/pdfsonline/wrk/wrk8/index.php

PARTICIPANTS

Working Group Members
Dr Vadim M. Govorun
Research Institute of Physico-Chemical
Medicine
Moscow, Russian Federation
govorun@hotmail.ru

Dr Christian C. Abnet
Division of Cancer Epidemiology &Genetics
National Cancer Institute
Bethesda, MD, USA
abnetc@mail.nih.gov

Dr E. Robert Greenberg
Fred Hutchinson Cancer ResearchCenterSeattle, WA, USA
E.Robert.Greenberg@dartmouth.edu

Dr Masahiro Asaka
Department of Cancer Preventive
Medicine
Hokkaido University Graduate Schoolof Medicine
Sapporo, Japanmaasaka@med.hokudai.ac.jp

Dr Yi-Chia Lee
Department of Internal Medicine
National Taiwan University College ofMedicine
Taipei, Taiwan, China
yichialee@ntu.edu.tw

Dr Il Ju Choi
Gastric Cancer Center
National Cancer Center
Goyang, Republic of Korea
cij1224@ncc.re.kr

Dr Mārcis Leja
Faculty of Medicine
University of Latvia
Riga, Latvia
cei@latnet.lv

Dr Pelayo Correa
Division of Gastroenterology,
Hepatology, and Nutrition
Vanderbilt University
Nashville, TN, USA
pelayo.correa@vanderbilt.edu

Dr Reza Malekzadeh
Digestive Disease Research Institute
Tehran University of Medical Sciences
Tehran, Islamic Republic of Iran
male@ams.ac.ir

Dr Catterina Ferreccio
Departamento de Salud
Pública/Escuela de Medicina
Pontificia Universidad Católica deChileSantiago, Chilecferrec@med.puc.cl

Dr Francis Mégraud
INSERM U853 & Bacteriology
Laboratory
University of Bordeaux
Bordeaux, France
francis.megraud@chu-bordeaux.fr

Dr Javier P. Gisbert
Department of Gastroenterology
Hospital Universitario de La Princesa
Instituto de Investigación Sanitaria
Princesa and CIBEREHD
Madrid, Spainjavier.p.gisbert@gmail.com

Dr Paul Moayyedi
Department of Medicine
McMaster University
Hamilton, ON, Canada
moayyep@mcmaster.ca

Dr Karen J. Goodman
Department of Medicine & School of
Public Health
University of Alberta
Edmonton, AB, Canada
karen.goodman@ualberta.ca

Dr Nubia Muñoz
National Cancer Institute of Colombia(Emeritus Professor)
Lyon, France
nubia.munoz@free.friii

Dr Catherine de Martel
Infections and Cancer Epidemiology
Group
Section of Infections
International Agency for Research on
CancerLyon, France
demartelc@iarc.fr

Dr Julie Parsonnet
Departments of Medicine and of
Health Research and Policy
Stanford University
Stanford, CA, USA
parsonnt@stanford.edu
Dr Javier Torres
Unidad de Investigación en
Enfermedades Infecciosas
Instituto Mexicano del Seguro Social
Mexico City, Mexico
jtorresl57@yahoo.com.mx

Dr David Forman
Head, Section of Cancer Information
International Agency for Research on
CancerLyon, France
formand@iarc.fr

Dr Nicholas J. Wald
Wolfson Institute of Preventive
Medicine
Barts and the London School of
Medicine and Dentistry
London, United Kingdom
n.j.wald@qmul.ac.uk

Dr Silvia Franceschi
Head, Infections and Cancer
Epidemiology Group
Section of Infections
International Agency for Research on
CancerLyon, France
franceschis@iarc.fr

Dr Wei-Cheng You
Peking University Cancer Hospital &Institute
Beijing, China
weichengyou@yahoo.com

Dr Paula Gonzalez
Prevention and Implementation Group
Section of Early Detection andPrevention
International Agency for Research on
CancerLyon, France
gonzalezp@iarc.fr

IARC Secretariat
Ms Karima Abdedayem
Prevention and Implementation Group
Section of Early Detection andPrevention
International Agency for Research on
CancerLyon, France
abdedayemk@iarc.fr

Dr Rolando Herrero
Head, Prevention and Implementation
Group
Section of Early Detection andPrevention
International Agency for Research on
CancerLyon, France
herreror@iarc.fr

Dr Maria Constanza Camargo
Prevention and Implementation Group
Section of Early Detection andPrevention
International Agency for Research on
CancerLyon, France
maria.camargo@nih.gov

Dr Jin Young Park
Prevention and Implementation Group
Section of Early Detection andPrevention
International Agency for Research on
CancerLyon, France
parkjy@fellows.iarc.fr

iv

Dr Martyn Plummer
Infections and Cancer Epidemiology
Group
Section of Infections
International Agency for Research on
CancerLyon, France
plummerm@iarc.fr
Dr Mónica S. Sierra
Section of Cancer Information
International Agency for Research on
CancerLyon, France
sierram@fellows.iarc.fr
Dr Massimo TommasinoHead, Infections and Cancer Biology
Group and Section of Infections
International Agency for Research on
CancerLyon, France
tommasinom@iarc.fr
Dr Christopher P. Wild
Director
International Agency for Research on
CancerLyon, France
director@iarc.frv

Table of Contents

ABBREVIATIONSVIIISUMMARY OF IARC WORKING GROUP MEETING ON HELICOBACTER PYLORI ERADICATION AS A
STRATEGY FOR PREVENTING GASTRIC CANCER

1

INTRODUCTION: THE CURRENT AND PROJECTED GLOBAL BURDEN OF GASTRIC CANCER

5SECTION 1: STATUS OF REGIONAL GASTRIC CANCER PREVENTION EFFORTS
CHAPTER 1.1: THE ROLE OF ENDOSCOPIC SCREENING IN GASTRIC CANCER CONTROL IN THE
REPUBLIC OF KOREA

16

CHAPTER 1.2: STRATEGY TO ELIMINATE GASTRIC CANCER DEATHS IN JAPAN21

CHAPTER 1.3: THE REGIONAL STATUS OF CURRENT OR PLANNED GASTRIC CANCER PREVENTIONSTRATEGIES IN TAIWAN, CHINA
28
CHAPTER 1.4: THE REGIONAL STATUS OF CURRENT OR PLANNED GASTRIC CANCER PREVENTIONSTRATEGIES IN LATIN AMERICA
37
CHAPTER 1.5: THE REGIONAL STATUS OF CURRENT OR PLANNED GASTRIC CANCER PREVENTIONSTRATEGIES IN EUROPE
44
CHAPTER 1.6: EFFECT OF HELICOBACTER PYLORI ERADICATION ON DIFFERENT SUBTYPES OF
GASTRIC CANCER: PERSPECTIVE FROM A MIDDLE EASTERN COUNTRY55

SECTION 2: HEALTH EFFECTS AND CONSEQUENCES OF HELI COBACTER P YLORIERADICATIONCHAPTER 2.1: EFFECTIVENESS OF HELICOBACTER PYLORI ERADICATION

64

CHAPTER 2.2: ARE THERE BENEFITS OF HELICOBACTER PYLORI INFECTION?

72

CHAPTER 2.3: POTENTIAL IMPACT OF BACTERIAL RESISTANCE AFTER POPULATION-BASEDHELICOBACTER PYLORI TREATMENT80

SECTION 3: COST–EFFECTIVENESS AND FEASIBILITY OF HELI COBACTER P YLORISCREENING AND TREATMENT PROGRAMMESCHAPTER 3.1: PRINCIPLES OF EVIDENCE-BASED CANCER PREVENTION STRATEGIES88

CHAPTER 3.2: POTENTIAL REGIMENS FOR THE MASS ERADICATION OF HELICOBACTER PYLORIINFECTION
95
CHAPTER 3.3: FEASIBILITY AND COST–EFFECTIVENESS OF POPULATION-BASED HELICOBACTER
111
PYLORI ERADICATIONCHAPTER 3.4: THE ROLE OF BIOMARKERS OF GASTRIC CANCER RISK TO TARGET INTERVENTIONS
122
CHAPTER 3.5: CURRENT AND ONGOING RESEARCH PROJECTS RELATED TO GASTRIC CANCERPREVENTION: PERSPECTIVE OF THE UNITED STATES NATIONAL CANCER INSTITUTE

136

SECTION 4: CURRENT AND PLANNED STUDIES OF THE POTENTIAL OF HELI COBACTERP YLORI TREATMENTS FOR GASTRIC CANCER REDUCTION
CHAPTER 4.1: CURRENT GASTRIC CANCER PREVENTION STRATEGIES IN LINQU COUNTY, A HIGHRISK AREA IN SHANDONG PROVINCE, CHINA
143
CHAPTER 4.2: MULTICENTRE RANDOMIZED STUDY OF HELICOBACTER PYLORI ERADICATION AND
PEPSINOGEN TESTING FOR PREVENTION OF GASTRIC CANCER MORTALITY (GASTRIC CANCERPREVENTION STUDY BY PREDICTING ATROPHIC GASTRITIS; GISTAR)
147
CHAPTER 4.3: EFFECT OF HELICOBACTER PYLORI ERADICATION ON GASTRIC CANCER PREVENTION
IN THE REPUBLIC OF KOREA: A RANDOMIZED CONTROLLED CLINICAL TRIAL
154
CHAPTER 4.4: COMMUNITY-BASED HELICOBACTER PYLORI ERADICATION WITH TWO SEQUENTIAL
ANTIBIOTIC REGIMENS FOR THE RESIDENTS AND MIGRANTS IN A HIGH-RISK AREA FOR GASTRICCANCER
161
CHAPTER 4.5: THE TREATMENT OF HELICOBACTER PYLORI INFECTION OF THE STOMACH IN
RELATION TO THE POSSIBLE PREVENTION OF GASTRIC CANCER

174

DISCLOSURES OF INTERESTS

181

Abbreviations
ASR
BUPA
13
C-UBT
CAG
CI
CI5
CYP
DDD
ELISA
ESCC
FIT
FOBT
G-17
GORD
GWAS
HPSA
HR
IARC
IgG
MALT
MAPS
miRNA
MG7-Ag
MHLW
NCI
NCSP
NHI
NHS
OA
OAM
OCM
OR
PAF
Pg
PPI
QALYs
RR
RUT
SNP
Th1
Treg
UBT
UGIS
WHO

age-standardized incidence rate
British United Provident Association
13
C-urea breath test
chronic atrophic gastritis
confidence interval
Cancer Incidence in Five Continents
cytochrome P450
defined daily dose
enzyme-linked immunosorbent assay
oesophageal squamous cell carcinoma
faecal immunochemical test
faecal occult blood test
gastrin-17
gastro-oesophageal reflux disease
genome-wide association studies
H. pylori stool antigen
hazard ratio
International Agency for Research on Cancer
immunoglobulin G
mucosa-associated lymphoid tissue
Management of precancerous conditions and lesions in the stomach
microRNA
gastric carcinoma-associated antigen
Japanese Ministry of Health, Labour and Welfare
United States National Cancer InstituteNational Cancer Screening Program of the Republic of Korea
National Health Insurance
National Health Service
omeprazole–amoxicillin
omeprazole–amoxicillin–metronidazole
omeprazole–clarithromycin–metronidazole
odds ratio
population attributable fraction
pepsinogenproton pump inhibitor
quality-adjusted life-years
relative risk
rapid urease test
single-nucleotide polymorphism
T helper 1
regulatory T cellurea breath test
upper gastrointestinal series
World Health Organizationviii

Summary of IARC Working Group Meeting on Helicobacter pylori
eradication as a strategy for preventing gastric cancer
Jin Young Park, E. Robert Greenberg, Julie Parsonnet, Christopher P. Wild, David
Forman, and Rolando Herrero, for the IARC Helicobacter pylori Working GroupThe International Agency for Research on Cancer (IARC) of the World Health Organization
convened a Working Group Meeting in December 2013 to review evidence regarding
Helicobacter pylori treatment as a strategy for preventing gastric cancer, the third leading
cause of cancer death globally. The burden of this disease is largely borne by populations inlow- and middle-income countries, where resources for treating advanced cancer are limited,so cost-effective prevention strategies are needed. The Working Group members included
19 external experts and 11 IARC participants. Their review included presentations on thefollowing topics: status of regional gastric cancer prevention efforts, health effects andconsequences of H. pylori eradication, cost–effectiveness and feasibility of H. pylori
screening and treatment programmes, and current and planned studies of the potential of H.
pylori treatments for gastric cancer reduction.
Status of regional gastric cancer prevention efforts
In 2012, an estimated 1 million new cases of gastric cancer and 720 000 gastric cancerrelated deaths occurred worldwide, the majority of them in East Asia, and nearly half in
China. Many other countries, especially in Latin America and eastern Europe, also haverelatively high rates of gastric cancer. Over the past four decades, incidence rates of gastriccancer have steadily declined in most populations, regardless of their background risk. Yet
despite an anticipated continued reduction in rates of approximately 2% per year, the futureburden of gastric cancer, in numbers of cases and deaths, is expected to rise as the world’s
population increases and ages.
Although gastric cancer has not been a public health priority worldwide, a few countries in
East Asia with a high burden of the disease have implemented control efforts. The Republicof Korea, where the age-standardized gastric cancer incidence rate is the highest globally,
has an established nationwide screening programme, which provides screening with either
upper gastrointestinal series (barium swallow) or endoscopy every 2 years to individuals
aged 40 years and older. In 2012, more than 12 million people were invited for screening,
and about half participated. In Japan, gastric cancer prevention efforts have primarily
focused on early detection using barium contrast imaging. However, screening has not been
widely accepted by the target population, and less than 10% were screened in 2010. The
emphasis is now shifting towards treating H. pylori, and in 2013 the Japanese government
approved national health insurance coverage for antibiotic treatment for H. pylori infection inpatients with endoscopically diagnosed chronic gastritis. In Changhua County, on the islandof Taiwan, China, organized gastric cancer prevention is included in a community-based
integrated screening programme that provides H. pylori stool antigen testing (as well as
faecal immunochemical testing for colorectal cancer screening); individuals who test positivefor H. pylori are offered endoscopic screening and antibiotic treatment.
In Latin America, Chile has introduced an opportunistic gastric cancer screening programmethat focuses on symptomatic adults aged 40 years and older. The programme provides
endoscopic examination for H. pylori detection, biopsy, and treatment. Other gastric cancer
prevention activities in Latin America have mainly entailed opportunistic endoscopy
screening conducted by private organizations, and they have resulted in limited population
coverage.

1

Health effects and consequences of H. pylori eradication
IARC classified H. pylori as a Group 1 carcinogen in 1994, and reconfirmed thisclassification in 2009. Approximately 89% of non-cardia gastric cancer cases, representing
78% of all gastric cancer cases, are now estimated to be attributable to chronic H. pylori
infection. Until relatively recently there were scant data from randomized clinical trials on theeffectiveness of treating H. pylori infection to reduce cancer risk. In 2012, long-term follow-up
results were reported from a randomized trial in Shandong, China, which found a statisticallysignificant 39% reduction in gastric cancer risk [1], and in 2014, a meta-analysis of allreported randomized trials estimated a relative risk of 0.66 (95% confidence interval, 0.46–0.95) [2]. Two trials have assessed the effect of H. pylori treatment after endoscopic mucosal
resection of early gastric cancer [3, 4]. One of the trials, in Japan, reported a statisticallysignificant reduction in risk of metachronous gastric cancer [3]. Risk also appeared lower in astudy in the Republic of Korea, but the result was not statistically significant [4]. Althoughthese results of randomized trials indicate that H. pylori treatment lowers gastric cancer
incidence by 30–40%, the available data do not permit precise estimation of overall benefits
and possible adverse consequences, and the results may not be widely generalizable.
Programmes of treating H. pylori infection may have other health effects, both positive andnegative. H. pylori is an important cause of peptic ulcer disease, and randomized trials of H.
pylori treatment have shown that it significantly reduces risk of new ulcer development. In
randomized trials conducted in the United Kingdom, community-based programmes of H.
pylori treatment resulted in fewer visits to medical facilities for dyspepsia symptoms. There isalso evidence that treating H. pylori can prevent anaemia. On the negative side, somestudies have suggested that H. pylori has immunological and physiological benefits; thus,
treatment to eradicate the organism might cause harm. A negative association between H.
pylori infection and oesophageal adenocarcinoma seems to be well established inepidemiological studies.
Epidemiological studies also have suggested a negative association between H. pylori
infection and asthma, eczema, and other immunological conditions, although the findings
overall are inconsistent and sometimes conflicting. Studies suggesting that H. pylori infection
may increase risk of other infectious diseases, including activation of latent tuberculosis, arethus far few in number, and their findings are not totally consistent. At the same time that H.
pylori and ulcer disease have been disappearing from many populations, gastrooesophageal reflux disease (GORD), Barrett oesophagus, and oesophageal
adenocarcinoma have been increasing. Meta-analyses have provided differing results as towhether risk of GORD is increased in those treated for H. pylori. There are plausible
physiological mechanisms by which H. pylori treatment could influence weight, but reported
associations between H. pylori treatment and weight gain have been inconsistent and of
relatively modest size.
At the population level, a programme of population screening and treatment for H. pylori
could plausibly increase the prevalence of antibiotic-resistant pathogens within thecommunity. In many countries, where indiscriminate use of antibiotics for human andveterinary purposes is common, it may be difficult to identify a particular effect of an H. pylori
treatment programme against the background of resistance due to use of antibiotics for otherpurposes. Concern would be increased if the H. pylori treatment regimen contained
antibiotics that are essential for treating serious human infections. At the individual level,
treatment for H. pylori infection selects for organisms that are resistant to the antibiotics
contained in the regimen used. H. pylori eradication treatment affects antibiotic resistance of
normal bacterial flora and will also alter the intestinal microbiome; however, adverse healthconsequences have not been demonstrated.

2

Cost–effectiveness and feasibility of H. pylori screening and treatment programmes
Programmes of H. pylori screening and treatment are likely to be feasible and relatively
affordable. An inexpensive blood test can be used to identify likely candidates for treatment;with a sensitivity of about 95% and a specificity of about 90%, this is not an ideal test but isperhaps acceptable for a population-based screening programme. The urea breath test andstool antigen test have at least as good sensitivity and higher specificity (better than 95%) for
active infection, but the cost and complexity of testing are higher.
Treatment regimens that contain two or three inexpensive, generic antibiotics plus a proton
pump inhibitor for 7–14 days can achieve greater than 80% success in eliminating H. pylori
infection, although effectiveness will vary according to the profile of antibiotic resistance inthe target population. Although the ideal approach would be a treatment chosen based on
culture and susceptibility testing, the most feasible approaches for population-based
treatment programmes will be either to use regimens that have been proven to be reliably
effective in the area or to select a regimen based on the observed pattern of antimicrobial
resistance in the target population.
Nine reports on health economic models have indicated that population H. pylori screening
and treatment strategies are cost-effective using a threshold of US$ 50 000 per life-year
saved. Some limitations of the published models are that they were based on observational
epidemiological data rather than on the more recently published results of randomized trials
evaluating H. pylori treatment to prevent gastric cancer, that most did not evaluate the costsavings from reducing dyspepsia in the population, that their estimates were based on yearsof life saved rather than quality-adjusted life-years, and that they did not consider possible
deleterious effects of treatment. Also, the absence of data from low-income countries limits
the utility of the analyses.
Gastric cancer is a multifactorial disease, and a combination of markers including hostgenetic factors, H. pylori virulence factors, and environmental factors such as diet may help
to identify patients at risk. However, the value of using markers to stratify on risk amongindividuals and to guide public health interventions is not established.
Current and planned studies of the potential of H. pylori treatments for gastric cancer
reduction
Several clinical trials that are currently under way should help to clarify whether and how to
implement population-based H. pylori screening and treatment programmes. The largest ofthese was initiated in 2011 in Linqu County in China. The trial is enrolling 200 000
participants aged 25–64 years from a high-risk population and is allocating them in arandomized cluster design to treatment with anti-H. pylori quadruple therapy or to control(low-dose omeprazole and bismuth citrate). Participants will be followed up for 10 years.
In the United Kingdom, the H. pylori Screening Study (HPSS) began in 1997, and was
designed to assess whether screening for and eradicating H. pylori infection in healthy men
aged 35–69 years and women aged 45–69 years would reduce the incidence of gastriccancer. The target number of participants was 56 000, with a planned follow-up of 15 years
or more after recruitment. Results should be available within the next few years.
A multicentre randomized study is proposed for Latvia, Belarus, and the Russian Federation,areas with a moderately high burden of gastric cancer. The objective is to evaluate whether
serum pepsinogen and H. pylori testing are effective in identifying high-risk subjects to bereferred for appropriate treatment with subsequent reduction in gastric cancer mortality. A
pilot study in Latvia was launched in 2013 to test the study procedures, assumptions, andacceptability of the methods.

3

In the Republic of Korea, a multicentre, randomized controlled trial commencing in 2014 will
evaluate the preventive efficacy and effectiveness of H. pylori treatment in reducing gastriccancer incidence among participants aged 40–60 years recruited from the nationwide cancer
screening programme. The goal is to define the possible role of H. pylori screening andtreatment in gastric cancer development within the context of a population-based screening
programme. The trial is scheduled to run for 10 years, with biennial endoscopic follow-up.
Conclusions and recommendations
The Working Group recognizes that gastric cancer is a disease of high importance for global
health, and it is likely to remain so for the foreseeable future unless effective control
measures are implemented. The continuing high global burden of gastric cancer and thefeasibility of treating its principal cause thus make it a logical target for intervention.
There is an acute need to commit more public health resources to gastric cancer control.
The Working Group recommends that all countries consider including gastric cancer in theirnational cancer control programmes and that they conduct detailed assessments of its
current and future human and economic impacts and of the potential value of prevention
strategies. Collecting standardized data on H. pylori prevalence will be useful for predicting
the future burden of gastric cancer and other H. pylori-associated conditions and may help toidentify subpopulations that appear most likely to benefit from interventions.
Randomized clinical trials have found that H. pylori treatment is effective in preventing
gastric cancer, and models indicate that H. pylori screening and treatment strategies would
be cost-effective. However, uncertainties remain about the generalizability of results andabout the cost–effectiveness and possible adverse consequences of programmes applied incommunity settings. The Working Group therefore recommends that countries explore thepossibility of introducing population-based H. pylori screening and treatment programmes,
but cautions that decisions as to whether and how to implement H. pylori testing andtreatment must hinge on local considerations of disease burden, other health priorities, andcost–effectiveness analyses. Moreover, these programmes should be implemented inconjunction with a scientifically valid assessment of programme processes, feasibility,
effectiveness, and possible adverse consequences.

References
1. Ma JL, Zhang L, Brown LM, Li JY, Shen L, Pan KF, et al. (2012). Fifteen-year effects of
Helicobacter pylori, garlic, and vitamin treatments on gastric cancer incidence andmortality. J Natl Cancer Inst. 104(6):488–92. http://dx.doi.org/10.1093/jnci/djs003
PMID:22271764
2. Ford ACF, Forman D, Hunt RH, Yuan Y, Moayyedi P (2014). Helicobacter pylori
eradication therapy to prevent gastric cancer in healthy asymptomatic infectedindividuals: systematic review and meta-analysis of randomised controlled trials. BMJ.
348:g3174. http://dx.doi.org/10.1136/bmj.g3174 PMID:24846275
3. Fukase K, Kato M, Kikuchi S, Inoue K, Uemura N, Okamoto S, et al.; Japan Gast Study
Group (2008). Effect of eradication of Helicobacter pylori on incidence of metachronous
gastric carcinoma after endoscopic resection of early gastric cancer: an open-label,randomised controlled trial. Lancet. 372(9636):392–7. http://dx.doi.org/10.1016/S01406736(08)61159-9 PMID:18675689
4. Choi J, Kim SG, Yoon H, Im JP, Kim JS, Kim WH, et al. (2014). Eradication of
Helicobacter pylori after endoscopic resection of gastric tumors does not reduceincidence of metachronous gastric carcinoma. Clin Gastroenterol Hepatol. 12(5):793–
800. http://dx.doi.org/10.1016/j.cgh.2013.09.057 PMID:24100112

4

Introduction
The current and projected global burden of gastric cancer
David Forman and Mónica S. Sierra
Gastric cancer is now the fifth most common malignancy in the world, after lung, breast,colorectal, and prostate cancer. The most recent estimates from GLOBOCAN 2012 [1]indicate that nearly 1 million (951 594) new gastric cancer cases and 723 027 deaths
occurred globally in 2012, accounting for 7% of the total new cancer cases and 9% of thetotal cancer deaths (Fig. 1).
Fig. 1. Estimated frequency of new cancer cases and deaths worldwide in 2012, for both sexes
combined. Source: Ferlay et al. (2013) [1].

The distribution of gastric cancer varies across geographical regions. In this chapter, we use
the term “less developed regions” to include all regions of Africa, Asia (excluding Japan),
Latin America and the Caribbean, Melanesia, Micronesia, and Polynesia, and the term “moredeveloped regions” to include all regions of Europe, North America, Australia, New Zealand,
and Japan. Among the 952 000 estimated new cancer gastric cancer cases that occurredworldwide in 2012, more than 70% (677 000 cases) were in less developed regions of theworld and 29% (275 000 cases) were in more developed regions. Asia contributed
approximately 74% (700 000 cases) to the global burden, and almost half of the cases in theworld occurred in China alone (405 000 cases). Europe contributed about 17% (162 000

5cases) to the global burden, whereas Latin America and the Caribbean contributed about 6%(61 000 cases) (Fig. 2).
Fig. 2. Estimated numbers of new gastric cancer cases and deaths in 2012, with proportions by major
world regions, for both sexes combined. Source: Stewart and Wild (2014) [2].

The geographical distribution of gastric cancer varies widely by sex. The estimated agestandardized (world) rates in 2012 among males were twice the rates among females(incidence per 100 000 person-years: 17.4 in males and 7.5 in females; mortality per
100 000 person-years: 12.7 in males and 5.7 in females). Among males, age-standardized
incidence rates ranged from 1.3 in Mozambique to 62.3 in the Republic of Korea (Fig. 3A),
whereas age-standardized mortality rates ranged from 1.2 in Mozambique to 37.1 inMongolia (Fig. 3B). Similar distributions were observed in females; however, the agestandardized incidence and mortality rates were uniformly lower than the corresponding
rates in males (Fig. 4A and 4B).

6

Fig. 3. (A) Estimated age-standardized (world) incidence rates of gastric cancer per 100 000 personyears by country among males in 2012. (B) Estimated age-standardized (world) incidence rates ofgastric cancer per 100 000 person-years by country among females in 2012. Source: Ferlay et al.
(2013) [1].

A

B

7

Fig. 4. (A) Estimated age-standardized (world) mortality rates of gastric cancer per 100 000 personyears by country among males in 2012. (B) Estimated age-standardized (world) mortality rates ofgastric cancer per 100 000 person-years by country among females in 2012. Source: Ferlay et al.
(2013) [1].

A

B

The global burden of gastric cancer described above must be interpreted with caution
because it is based on estimates from GLOBOCAN 2012, which are subject to precision anddata quality limitations. Although GLOBOCAN presents the best available estimates, they
are dependent on the availability and quality of cancer incidence and mortality data for eachcountry, and when such information is lacking (as in many developing countries), estimates
are created using frequency data or rates of the neighbouring countries [1]. Therefore, it isimportant to consider in addition the more reliable incidence information derived directly from8

population-based cancer registries. Every 5 years, IARC publishes data from selected
population-based cancer registries with high-quality data in Cancer Incidence in Five
Continents (CI5). The current CI5 volume (Volume X) includes 290 cancer registries from 68
countries with information on cancers diagnosed between 2003 and 2007 [3]. Table 1
summarizes the cancer registries with some of the highest and lowest gastric cancer rates in
the world. For example, the incidence rates of gastric cancer among males in the Republic ofKorea and Japan are almost 15 times the rates observed among White males in Florida in
the USA.
Table 1. Cancer registries with high and low age-standardized (world) incidence rates of gastriccancer, males, 2003–2007
Registry

ASR

Registry

ASR

Republic of Korea, Daejeon

75.4

Libyan Arab Jamahiriya, Benghazi

4.9Japan, Hiroshima

72.5

USA, Florida, White

4.9

India, Mizoram

50.6

Saudi Arabia, Riyadh, Saudi

4.4

Chile, Biobio

41.2

USA, Utah

4.0

USA, Los Angeles, Korean

39.4

Malaysia, Penang, Malay

3.5

Belarus

33.3

India, New Delhi

3.2

China, Jiashan

32.5

Kuwait3.0

Russian Federation, St Petersburg

29.0

Egypt, Gharbiah

2.9

Costa Rica

26.5

Thailand, Khon Kaen

2.5

Colombia, Cali

26.0

Malawi, Blantyre

2.0

ASR, age-standardized (world) incidence rate per 100 000 person-years.
Source: Compiled from Forman et al. (2013) [3].

Overall, the patterns of gastric cancer incidence and mortality are very similar because
prognosis after a diagnosis of gastric cancer is usually poor [4]. However, mortality rates inJapan and the Republic of Korea are considerably lower than incidence rates, which could
reflect the impact of screening and early diagnosis in those countries.
1. Incidence trends over time
Cancer registry data can be used to analyse trends over time. Fig. 5 shows the trends inoverall age-standardized (world standard population) gastric cancer rates for males andfemales for cancer registries included in all 10 volumes of CI5 between 1958 and 2007; plots
represent age-standardized rates for each 5-year period (1960–2005). Over the 45-year
period, the age-standardized incidence rates have steadily declined in nearly all populations.
Trends for males and females in each population are very similar. The pattern is common for
all selected areas regardless of the background risk of gastric cancer. For instance, in areas
with historically high gastric cancer rates, such as Japan and Colombia, similar decreasing
trends have been noted in more recent years.
The marked geographical variation of gastric cancer and the remarkable decline in incidence
suggest that this decline may be related to the reduction of ubiquitous exposures worldwide.

9

Improvements in sanitation and preservation and storage of foods, changes in theprevalence of Helicobacter pylori infection, and use of antibiotics are thought to be
responsible for these declines [4–6].
2. Cardia and non-cardia gastric cancer
There is increasing interest in the distribution of gastric cancers by subsite of the stomach
because cancers arising from the most proximal cardia region and distal region (non-cardia)
are likely to have different etiologies [4]. A pooled analysis of 12 case–control studies nested
within prospective cohorts revealed that the risk of developing non-cardia gastric cancer
among individuals who were H. pylori seropositive ≥ 10 years before cancer diagnosis was 6times that among H. pylori-negative individuals [7]. GLOBOCAN 2012 estimates of thenumber of cardia and non-cardia gastric cancer cases revealed a variation by world region.
For example, East Asia accounted for 61% of all non-cardia gastric cancers, whereas lessthan 3% of cases occurred in sub-Saharan Africa, North America, and Oceania (Table 2).
Table 2. Estimated numbers of gastric cancers and non-cardia gastric cancers by world region, 2012aRegionCardiaNon-cardia

Sub-Saharan Africa

18 00018 000

North Africa and West Asia

23 000

20 000Central Asia

96 00086 000

East Asia

587 000

504 000

South America

61 00057 000

North America

25 00017 000Eastern Europe

70 00062 000

North-western Europe

40 00030 000Southern Europe

30 00027 000Oceania

3000

20 000World

952 000

823 000a

Estimated using proportions of non-cardia cancers within all microscopically verified gastric cancers within
registries in Cancer Incidence in Five Continents, Volume X [3], stratified by region, sex, and age group (J.
Ferlay, personal communication).

10Fig. 5. Gastric cancer: age-standardized (world) incidence rates by 5-year period for cancer registries in all 10 volumes of Cancer Incidence in Five
Continents: (left) males, all ages; (right) females, all ages. Source: Forman et al. (2013) [3].

11

A recent analysis of gastric cancer incidence by subtype revealed a wide variation in the
proportion of cardia gastric cancers worldwide [8]. For instance, in men the proportion ofcardia cases among those with topography defined as cardia or non-cardia was 5.8% in the
Republic of Korea, 13.1% in Ecuador, and 72.0% in Finland. Similar patterns were also
described in women, even though the number of cancer cases was small.
3. Global burden of H. pylori-associated cancers
H. pylori infection has been classified by IARC as a human carcinogen [9]. Investigators
have attempted to estimate the proportion of gastric cancer cases that could have been
avoided if exposure to H. pylori infection was absent. De Martel et al. [10] estimated apopulation attributable fraction (PAF) by using the prevalence of H. pylori infection in gastriccancer cases of 90% (as measured by antibodies in blood serum with the enzyme-linked
immunosorbent assay [ELISA]) and a relative risk of 5.9, and obtained a PAF estimate of
74.7%. If this PAF is applied to global incidence estimates from 2008, approximately
650 000 new gastric cancer cases would be attributable to H. pylori infection [10]. Theseestimates indicate that infection with H. pylori could be responsible for approximately
470 000 new cancer cases in less developed regions of the world and for 190 000 in moredeveloped regions [10]. Plummer et al. [11] estimated a revised PAF based on a prevalenceof H. pylori in gastric cancer cases of 94.6% (as measured by immunoblot [western blot]
rather than ELISA) and a relative risk of 17.0, which resulted in a PAF of 89.0%. If this new
PAF is applied to the GLOBOCAN 2008 estimates, approximately 774 000 new non-cardia
gastric cancer cases would be attributable to H. pylori infection. If the most recent PAF
estimate (89.0%) is applied to the GLOBOCAN 2012 estimates, approximately 734 000 noncardia gastric cancer cases would be attributable to H. pylori infection. Fig. 6 shows theestimated annual burden of H. pylori-associated cancer by world region in 2012.
PAF estimates are largely dependent on accurate estimates of prevalence of H. pylori
infection and the estimates of risk; uncertainties in these estimates inevitably lead to
uncertainty in the PAF calculation. In spite of the inherent limitations of these calculations,they provide the most reasonable and up-to-date estimates of non-cardia gastric cancer
attributable to H. pylori infection worldwide.

12

Fig. 6. Estimated annual burden of Helicobacter pylori-associated cancer by world region (2012).

13

4. Predicted burden of gastric cancer, 2012–2030
Assuming that the risk of gastric cancer remains stable in all countries, the global burden(annual number of new cases) of this form of cancer worldwide is expected to increase by2030. The increase is expected to be driven primarily by the growth and ageing of the
population (Table 3). However, if the currently observed decline in incidence rates remains
at a constant level, then the global burden is estimated to be maintained at an approximately
constant level.
Table 3. Predicted burden of gastric cancer, 2012–2030
Year

Annual number of new gastric cancer cases (millions)
Demographic effect

Demographic and –2.0% APC

2012

0.95

0.95

2015

1.03

0.97

2020

1.17

1.00

2025

1.34

1.03

2030

1.52

1.06

APC, annual percentage change.
Sources: Ferlay et al. (2013) [1] and J. Ferlay, personal communication.

5. Conclusion
In 2012 approximately 952 000 new gastric cancer cases occurred globally, of which
823 000 were at non-cardia sites. The main burden continues to fall in Asia, South America,and eastern Europe. In 2012 approximately 734 000 gastric cancers were estimated to be
attributable to H. pylori infection. The burden of gastric cancer is likely to remain constanteven with declining age-standardized incidence.

References
1. Ferlay J, Soerjomataram I, Ervik M, Dikshit R, Eser S, Mathers C, et al. (2013).
GLOBOCAN 2012 v1.0, Cancer Incidence and Mortality Worldwide: IARC CancerBase
No. 11 [Internet]. Lyon, France: International Agency for Research on Cancer. Available
from: http://globocan.iarc.fr
2. Stewart BW, Wild CP, editors (2014). World cancer report 2014. Chapter 5.4: Stomach
cancer. Lyon, France: International Agency for Research on Cancer.
3. Forman D, Bray F, Brewster DH, Gombe Mbalawa C, Kohler B, Piñeros M, et al., editors(2013). Cancer incidence in five continents, Vol. X [electronic version]. Lyon, France:
International Agency for Research on Cancer. Available from: http://ci5.iarc.fr
4. de Martel C, Forman D, Plummer M (2013). Gastric cancer: epidemiology and risk factors.
Gastroenterol Clin North Am. 42(2):219–40. http://dx.doi.org/10.1016/j.gtc.2013.01.003
PMID:23639638
5. Bosetti C, Malvezzi M, Chatenoud L, Negri E, Levi F, La Vecchia C (2005). Trends incancer mortality in the Americas, 1970–2000. Ann Oncol. 16(3):489–511.
http://dx.doi.org/10.1093/annonc/mdi086 PMID:15668262
6. Parkin DM, Bray F, Ferlay J, Pisani P (2005). Global cancer statistics, 2002. CA Cancer J
Clin. 55(2):74–108. http://dx.doi.org/10.3322/canjclin.55.2.74 PMID:15761078

14

7. Helicobacter and Cancer Collaborative Group (2001). Gastric cancer and Helicobacter
pylori: a combined analysis of 12 case control studies nested within prospective cohorts.
Gut. 49(3):347–53. http://dx.doi.org/10.1136/gut.49.3.347 PMID:11511555
8. Ferro A, Peleteiro B, Malvezzi M, Bosetti C, Bertuccio P, Levi F, et al. (2014). Worldwide
trends in gastric cancer mortality (1980–2011), with predictions to 2015, and incidenceby subtype. Eur J Cancer. 50(7):1330–44. http://dx.doi.org/10.1016/j.ejca.2014.01.029
PMID:24650579
9. IARC (2012). Biological agents. IARC Monogr Eval Carcinog Risks Hum. 100B:1–441.
PMID:23189750
10. de Martel C, Ferlay J, Franceschi S, Vignat J, Bray F, Forman D, et al. (2012). Global
burden of cancers attributable to infections in 2008: a review and synthetic analysis.
Lancet Oncol. 13:607–15. http://dx.doi.org/10.1016/S1470-2045(12)70137-7
PMID:22575588
11. Plummer M, Franceschi S, Vignat J, Forman D, de Martel C (2014). Global burden ofgastric cancer attributable to Helicobacter pylori. Int J Cancer. [Epub ahead of print]
http://dx.doi.org/10.1002/ijc.28999

15

Chapter 1.1
The role of endoscopic screening in gastric cancer control in the
Republic of Korea
Il Ju Choi
Although the incidence of gastric cancer has declined in many countries during the past
century, it is still the fifth most commonly diagnosed cancer and the third leading cause ofcancer death globally [1]. In the Republic of Korea, about 30 000 gastric cancer cases are
diagnosed per year, and this was the most common type of cancer until 2010 (when thyroid
cancer took the top place) [2, 3]. In 2010, gastric cancer remained the leading type ofincident cancer (19.6% of all cancers) in men and was the fourth most common cancer(10.0% of all cancers) in women. Mortality data in 2011 showed that gastric cancer is thethird leading cause of cancer death (14.1% of all cancer deaths) in men and the second
leading cause in women (12.7% of all cancer deaths) [3].
The 5-year relative survival rates for gastric cancer have increased over the past 15 years in
the Republic of Korea (from 42.8% in 1993–1995 to 67.0% in 2006–2010) [3]. However, theage-standardized incidence (rate per 100 000 people) of gastric cancer did not show any
significant changes during the past decade (67.2 in 2001 and 62.3 in 2010 for men; 26.2 in2001 and 24.9 in 2010 for women) [3, 4].
1. National Cancer Screening Program
The National Health Insurance (NHI) programme of the Republic of Korea is a mandatorysocial insurance system that covers the whole population [5]. It is financed throughcontributions paid by the beneficiaries and their employers, as well as the government.
Patients are allowed to choose medical service providers at their preference almost without
restrictions, except for the payment of a certain level of premium. Providers are primarily
paid by a fee-for-service system. Medical services are provided to very-low-income
households through the Medical Aid programme to secure the minimum livelihood of thosehouseholds.
In 1996, the government of the Republic of Korea implemented the first 10-Year Plan for
National Cancer Control [5]. The objective of the first term was to develop infrastructure byestablishing cancer control programmes such as the Cancer Control Law and launching the
National Cancer Center and regional cancer centres. The second term of the 10-year Plan
for National Cancer Control began in 2006, to strengthen cancer control efforts at the
government level and aimed at reducing the economic burden of cancer significantly by
reducing cancer incidence and mortality through systemic cancer management [6].
The government of the Republic of Korea established the National Cancer Screening
Program (NCSP) in 1999 in an effort to reduce the burden of cancer [7]. Until 2001, the
NCSP provided Medical Aid recipients with screening free of charge for three types ofcancer (gastric, breast, and cervical cancer). Since then, the target population and types ofcancer covered have been expanded. NHI beneficiaries in the lower 20% income bracket
were included in the NCSP in 2002 and those in the lower 30% in 2003. Liver cancer was
included in 2003 and colorectal cancer in 2004. Since 2005, the NCSP has provided Medical
Aid recipients and NHI beneficiaries in the lower 50% income bracket with screenings for five
types of cancer (gastric, liver, colorectal, breast, and cervical cancer). NHI beneficiaries in
the upper 50% income bracket receive screening services for the same five types of cancerfrom the NHI Corporation; however, they are required to pay 10% of the cost. Thus, currently

16almost all people of eligible age in the Republic of Korea are provided with a cancer
screening programme for free or at minimal cost.
The guidelines of the NCSP are listed in Table 1.1.1 [8, 9]. The NCSP provides gastriccancer screening every 2 years for those aged 40 years or older. Participants can choose
either upper gastrointestinal series (UGIS) or endoscopy according to their preference. If
UGIS is chosen and reveals any abnormal finding indicating gastric cancer, then endoscopy
is provided to confirm what the abnormality is. Biopsy for any abnormal finding duringendoscopy that requires histological evaluation is also covered by the NCSP.
In addition to these organized cancer screening programmes provided by the government,
opportunistic cancer screening is widely available in the Republic of Korea. Organizedcancer screening programmes use nationally implemented protocols that define a target
population, screening interval, and follow-up strategies. However, opportunistic cancer
screening programmes include a variety of options in terms of the target cancer, screening
interval, and screening method, depending on the programmes chosen by the participants ortheir employers. All costs of opportunistic cancer screening are paid entirely by users,
without a government subsidy.
Table 1.1.1. Guidelines of the National Cancer Screening Program of the Republic of Korea
CancerTarget population

Gastric

Aged 40 years and older

Liver

Interval (years)

Test

2

Upper endoscopy or UGIS

High-risk group aged 40 years and
older

1

Ultrasonography and AFP

Colorectal

Aged 50 years and older

1

FOBT

Breast

Women aged 40 years and older

2

Mammography

Cervical

Women aged 30 years and older2

Pap smearbac

AFP, α-fetoprotein; FOBT, faecal occult blood test; UGIS, upper gastrointestinal series.
a

In the case of an abnormality on UGIS, endoscopy is recommended for further evaluation and biopsy.

b

Patients at high risk for liver cancer include those with chronic hepatitis determined from serological evidence of
infection with hepatitis B or C virus or liver cirrhosis.
c

In the case of an abnormality on FOBT, colonoscopy or a double-contrast barium enema is recommended.

Sources: Suh et al. (2013) [8] and National Cancer Center (2013) [9].

2. Trends in gastric cancer screening
The target population of the NCSP consists of those insured by Medical Aid and the NHI
programme [7]. The number of screened Medical Aid recipients increased from 238 762 in
2002 to 730 730 in 2011 [4]. The number of screened NHI beneficiaries increased from533 343 in 2002 to 6 284 780 in 2011. In 2011, among the five cancers in the NCSP, gastriccancer was the most common type of cancer screened for (3 033 674). The overall rate ofparticipation in the NCSP was 41.9% in 2011 (28.1% of Medical Aid recipients and 44.1% of
NHI beneficiaries); this rate increases each year.
The NCSP and NHI cancer screening offered gastric cancer screening to 12 655 502 people
in 2011; the actual number of participants was 5 820 296 (46.0%). This figure shows asignificant increase compared with only 7.7% of the potential candidates in 2002.

17

Two types of cancer screening rates were used to estimate trends. “Lifetime screening rate”
was defined as having experienced each type of screening test. The “screening rate withrecommendation” category was assigned to participants who had undergone screening tests
according to the protocols of the NCSP. The Korean National Cancer Screening Survey, anationwide, population-based, cross-sectional survey, has been conducted annually by the
National Cancer Center since 2004. Stratified multistage random sampling based onresident registration population data is conducted according to geographical area, age, andsex [8]. In 2004, lifetime screening rates and screening rates with recommendation for
gastric cancer were 52.0% and 39.2%, respectively. These figures continuously increased,reaching 77.9% and 70.9%, respectively, in 2012. Thus, the estimated annual percentagechange was a 4.0% increase for lifetime screening rate and a 4.3% increase for screening
rate with recommendation [8]. One of the goals of the second-term 10-year Plan for National
Cancer Control (2006–2015) was to increase screening rates with recommendation to 70%
by 2015 [5]. For gastric cancer this goal was achieved ahead of time, in 2012.
3. Performance of gastric cancer screening: comparison of UGIS and endoscopy
In 2002, about 74.7% of participants underwent UGIS and 24.8% underwent endoscopy. In
2011, the proportions were reversed: about 70.8% of participants chose endoscopy.
Although the NCSP offers either UGIS or upper endoscopic examination as the initial
screening method for gastric cancer, at the time the NCSP was initiated there was a lack ofagreement on which screening method works better [10]. A study compared the cost andaccuracy of UGIS and endoscopy for gastric cancer diagnosis using NCSP data from 2002–
2004 [10]. Of the 1 067 378 people screened with UGIS, 892 gastric cancer cases weredetected, and of the 436 268 participants screened with upper endoscopy, 1041 gastriccancer cases were detected. The probability of detecting gastric cancer through endoscopy
was 2.9 times that through UGIS. The unit costs of screening using UGIS and endoscopy
were similar in the Republic of Korea, at US$ 32.67 and US $34.89, respectively. Thus, theestimated cost of identifying one case of gastric cancer was US$ 53 000 using UGIS and
US$ 16 900 using endoscopy, for a ratio of 3.7:1.
A more recent study evaluated the relative performance of UGIS and endoscopic screening
using NCSP data from 2002–2005 [11]. Gastric cancer detection rates were 0.68 per 1000UGIS and 2.61 per 1000 endoscopic screenings. The sensitivities of UGIS and endoscopic
screening for detecting gastric cancer were 36.7% and 69.0%, respectively, and their
specificities were 96.1% and 96.0%, respectively. Gastric cancer cases detected byendoscopic screening were at the localized stage in 45.7% of cases, whereas the figure for
UGIS was 32.4%. Because tumour stage is the most important prognostic factor after cancer
diagnosis, the performance of endoscopy can be considered to be far better than that ofUGIS.
A recent study evaluated the cost–effectiveness outcomes of the gastric cancer screening
programme of the NCSP using the target population who participated in the screening
programme during 2002–2003 [12]. The study showed that incremental cost–effectivenessratio estimates for life-years saved indicate that the gastric cancer screening programme in
the Republic of Korea is cost-effective for both men and women. An upper limit of 75 or
80 years for screening age was suggested in men. Because endoscopy was a more costeffective strategy than UGIS for both men and women, the study suggested that endoscopy
should be recommended as the first-line method in the Republic of Korea.
Taking into account the improved quality of available equipment and the skill ofendoscopists, endoscopic screening is expected to exhibit far better performance nowadays

18

compared with that seen 10 years ago during the initial periods of the NCSP. The issue ofthe upper limit for screening age should be evaluated in future studies.
4. Screening interval
The NCSP gastric cancer screening programme recommends biennial examination for both
UGIS and endoscopy. Because there had previously been no adequate study evaluating thescreening interval, a study investigated whether repeated endoscopy screening is aneffective method for detecting early gastric cancer that can be treated by endoscopic
resection [13]. Of the 18 414 patients who underwent opportunistic endoscopy at the
National Cancer Center, 81 (0.44%) were found to have gastric cancer. The incidence ofgastric cancer in the group that underwent repeated screening within 2 years was lower thanthat in the group that underwent infrequent screening (adjusted odds ratio, 0.45; 95%
confidence interval, 0.26–0.77). In the group that underwent repeated screening within
2 years, the proportion of early gastric cancers was 96% (25 of 26), and endoscopic
treatment for detected gastric cancer was possible in 54% (14 of 26) of these cases.
Another study evaluated the association of the interval between endoscopies with gastriccancer stage at diagnosis in 2485 gastric cancer patients referred to the National Cancer
Center [14]. A significant benefit in cancer stage at diagnosis was observed in all intervalgroups (1-year, 2-year, 3-year, 4-year, 5-year, and > 5-year intervals) compared with neverscreened patients. Compared with the 1-year interval group, the risk of advanced gastriccancer was increased in the 4-year and 5-year interval group, but not in the 2-year and 3year interval groups. These data suggest that endoscopy intervals of 3 years or shorter show
similar benefits.
Whether the 2-year screening interval can be applied for both UGIS and endoscopy, whichhave different performances in the context of the NCSP, has not yet been adequately
evaluated. Moreover, it is unknown whether there are high-risk groups suitable for shorter
screening intervals or a low-risk population for whom a longer screening interval is sufficientor who do not need screening at all.
5. Conclusions
The Republic of Korea has one of the highest incidence and mortality burdens from gastriccancer worldwide and has a unique programme for screening the general population. There
are many aspects of the screening conditions and outcomes that require adequate
evaluation to assess the gastric cancer screening programme in the setting of the Republicof Korea. One of the main issues is that the effect of screening on the gastric cancer
mortality rate has not yet been proven, although a continuously decreasing trend in gastriccancer mortality is seen. Moreover, cost–effectiveness analysis should be performed using
more recent data, which are derived from a much larger pool of participants and a highquality endoscopy system. The adequacy of the screening interval and the age at which tobegin and end screening also need validation. The incorporation of different screening
strategies by risk stratification, or of primary prevention tools such as Helicobacter pylori
eradication, is needed in the future to improve the performance and cost–effectiveness of
the NCSP.

References
1. Ferlay J, Soerjomataram I, Ervik M, Dikshit R, Eser S, Mathers C, et al. (2013).
GLOBOCAN 2012 v1.0, Cancer Incidence and Mortality Worldwide: IARC CancerBase
No. 11 [Internet]. Lyon, France: International Agency for Research on Cancer. Available
from: http://globocan.iarc.fr

19

2. Jung KW, Park S, Kong HJ, Won Y-J, Lee JY, Seo HG, et al. (2012). Cancer statistics in
Korea: incidence, mortality, survival, and prevalence in 2009. Cancer Res Treat.
44(1):11–24. http://dx.doi.org/10.4143/crt.2012.44.1.11 PMID:22500156
3. Jung KW, Won YJ, Kong HJ, Oh C-M, Seo HG, Lee J-S (2013). Cancer statistics in
Korea: incidence, mortality, survival and prevalence in 2010. Cancer Res Treat. 45(1):1–
14. http://dx.doi.org/10.4143/crt.2013.45.1.1 PMID:23613665
4. National Cancer Control Institute (2013). Cancer facts and figures 2013 in the Republic ofKorea, 1st ed. Seoul, Republic of Korea: Ministry of Health and Welfare, National Cancer
Center.
5. Yoo KY (2008). Cancer control activities in the Republic of Korea. Jpn J Clin Oncol.
38(5):327–33. http://dx.doi.org/10.1093/jjco/hyn026 PMID:18407932
6. Han MA, Choi KS, Park JH, Moore MA, Park EC (2011). Midcourse evaluation of thesecond-term 10-year plan for cancer control in Korea. Asian Pac J Cancer Prev.
12(1):327–33. PMID:21517281
7. Kim Y, Jun JK, Choi KS, Lee HY, Park EC (2011). Overview of the National Cancer
screening programme and the cancer screening status in Korea. Asian Pac J Cancer
Prev. 12(3):725–30. PMID:21627372
8. Suh M, Choi KS, Lee YY, Jun JK (2013). Trends in cancer screening rates among Korean
men and women: results from the Korean National Cancer Screening Survey, 2004–
2012. Cancer Res Treat. 45(2):86–94. http://dx.doi.org/10.4143/crt.2013.45.2.86
PMID:23864841
9. National Cancer Center (2013). Cancer facts & figures in the Republic of Korea, 2013.
Goyang, Republic of Korea: National Cancer Center. Available from:http://ncc.re.kr/english/cyber/publi01.jsp
10. Lee HY, Park EC, Jun JK, Choi KS, Hahm MI (2010). Comparing upper gastrointestinal
X-ray and endoscopy for gastric cancer diagnosis in Korea. World J Gastroenterol.
16(2):245–50. http://dx.doi.org/10.3748/wjg.v16.i2.245 PMID:20066745
11. Choi KS, Jun JK, Park EC, Park S, Jung KW, Han MA, et al. (2012). Performance ofdifferent gastric cancer screening methods in Korea: a population-based study. PLoS
One. 7(11):e50041. http://dx.doi.org/10.1371/journal.pone.0050041 PMID:23209638
12. Cho E, Kang MH, Choi KS, Suh M, Jun JK, Park E-C (2013). Cost-effectivenessoutcomes of the national gastric cancer screening program in South Korea. Asian Pac J
Cancer Prev. 14(4):2533–40. http://dx.doi.org/10.7314/APJCP.2013.14.5.2533
PMID:23725170
13. Nam SY, Choi IJ, Park KW, Kim CG, Lee JY, Kook M-C, et al. (2009). Effect of repeatedendoscopic screening on the incidence and treatment of gastric cancer in healthscreenees. Eur J Gastroenterol Hepatol. 21(8):855–60.
http://dx.doi.org/10.1097/MEG.0b013e328318ed42 PMID:19369882
14. Nam JH, Choi IJ, Cho SJ, Kim CG, Jun JK, Choi KS, et al. (2012). Association of theinterval between endoscopies with gastric cancer stage at diagnosis in a region of highprevalence. Cancer. 118(20):4953–60. http://dx.doi.org/10.1002/cncr.27495
PMID:22806878

20

Chapter 1.2
Strategy to eliminate gastric cancer deaths in Japan
Masahiro Asaka
In 2008, a randomized multicentre clinical study conducted in Japan revealed that
eradication of Helicobacter pylori reduced the incidence of secondary gastric cancer by
about two thirds after endoscopic mucosal resection of early gastric cancer, suggesting theusefulness of H. pylori eradication for prevention of gastric cancer [1]. However, that study
also showed that H. pylori eradication did not completely eliminate gastric cancer. Thus, toachieve the elimination of gastric cancer in Japan, the important issue is how to combine
primary prevention through H. pylori eradication with secondary prevention throughsurveillance. Fortunately, the Japanese Ministry of Health, Labour, and Welfare (MHLW)
approved national health insurance coverage for eradication therapy in patients with gastritis
caused by H. pylori infection (chronic active gastritis) on 21 February 2013, for the first timein the world [2].
1. Current status and characteristics of screening for gastric cancer in JapanThe concept of early gastric cancer was proposed in Japan in 1963 [3, 4]. At that time, earlygastric cancer was defined as a lesion with infiltration of tumour cells limited to the mucosa
or submucosa, irrespective of lymph node metastasis. The prognosis of early gastric cancer
is far better than that of advanced cancer, with a 5-year survival rate of more than 90% inJapan [5, 6]. Therefore, many studies in Japan have focused on how to effectively diagnose
early gastric cancer. As a result, early gastric cancer now accounts for nearly 60% of all
gastric cancers detected in Japan [7]. In other countries, including the USA and countries in
Europe, the 5-year survival rate of gastric cancer patients is reported to be only 10–25% [8].
This is not because treatment of gastric cancer in Japan is superior to that in other countries
but because the detection rate of early cancer is much lower outside Japan [9]. It is also
likely that the impressive 5-year survival results seen in Japan are in part attributable to leadtime and length-time bias as well as the possibility that some cancers are overdiagnosed[10].
In Japan, the prevention of cancer, including gastric cancer, has primarily focused on
secondary measures for early detection of cancer, rather than on primary prevention aimed
at elimination of the causes. Indirect barium contrast imaging has been used as thescreening method for gastric cancer, but despite the long interest and emphasis, thescreening rate was only 9.6% in 2010 [11]. Also, screening for gastric cancer based on
barium contrast imaging does not have a high sensitivity for detecting early cancer [11] andis associated with considerable exposure to radiation. Furthermore, targeting all people aged
40 years or older for screening is a major problem as people aged younger than 50 years
account for only about 3% of all gastric cancer patients in Japan [11]. Moreover, H. pylorinegative patients with minimal or no atrophy of the gastric mucosa are very unlikely todevelop gastric cancer; thus, these patients are unlikely to benefit from annual barium
contrast screening and are still exposed to the adverse effects of radiation.
2. Prevention of gastric cancer by eradication of H. pylori
Assessment of the design of a new prospective study on the basis of previous studies
indicated that a clinical trial with a small sample size and short follow-up period should enrol
patients with early gastric cancer who have undergone endoscopic mucosal resection, since
they represent the population most likely to develop advanced gastric cancer. The annual
incidence of gastric cancer has been reported to be only 0.1–0.4% in H. pylori-positive21

patients with atrophic gastritis [12, 13], whereas the annual incidence of metachronousrecurrence is far higher (3–5%) in patients who have undergone endoscopic surgery forearly gastric cancer [14, 15]. The Japan Gast Study Group randomized multicentre clinical
trial investigated the metachronous recurrence of gastric cancer in 544 patients who had
undergone endoscopic treatment for early gastric cancer. They were randomly allocated toH. pylori eradication or non-eradication groups and were followed up by annual endoscopic
examination for 3 years. As a result, metachronous recurrence was detected in 9 subjects
from the eradication group and 24 subjects from the non-eradication group, and those in theeradication group had a significantly lower relapse rate (P < 0.01 according to intention-totreat analysis) [1].
After the Japan Gast Study Group trial was completed and data obtained at 8–10 years wereanalysed, it was found that there was still a difference in the incidence of metachronous
gastric cancer between the H. pylori eradication and non-eradication groups [16]. This
indicates that the preventive effect of eradication therapy on gastric cancer persists for along time.
3. Significance of health insurance coverage for H. pylori eradication therapy in Japan
Since it has become clear that most gastric cancer is due to H. pylori infection rather thanlifestyle factors, it is time for major revision of the preventive strategies for gastric cancer.
When it is suspected that a cancer is caused by infection, proactive preventive measures arelikely to lead to a dramatic decrease in the incidence of that cancer, resulting in a significant
decrease of cancer mortality. In Japan, preventive measures for liver cancer have been
focused on hepatitis virus infection since 2002, leading to a reduction of mortality [17, 18].
However, the annual number of deaths from gastric cancer has remained at about 50 000 for
the past few decades [19], suggesting that the current preventive measures are inadequate.
In 2009, the Japanese Society for Helicobacter Research published a guideline in which it isrecommended that all H. pylori-infected people receive bacterial eradication therapy [20]. In
response to this, the MHLW approved the extension of national health insurance coverage to
H. pylori eradication therapy for three indications (i.e. patients with gastric mucosaassociated lymphoid tissue [MALT] lymphoma, patients who have undergone endoscopic
surgery for early gastric cancer, and patients with idiopathic thrombocytopenic purpura[ITP]), in addition to patients with gastric and duodenal ulcers. This was the first time in theworld that insurance coverage has been provided for H. pylori eradication therapy forindications other than gastric and duodenal ulcers and represents an innovative approach.
Regarding the potential expansion of health insurance coverage for eradication therapy toinclude patients with chronic gastritis, the Japanese Society of Gastroenterology, the Japan
Gastroenterological Endoscopy Society, and the Japanese Society for Helicobacter
Research submitted a joint petition to the Minister of the MHLW. This public knowledgebased application led to the inclusion of H. pylori eradication therapy for patients with chronic
gastritis on 21 February 2013. The MHLW notification states that eradication therapy iscovered by the national health insurance scheme when a patient with endoscopicallydiagnosed chronic gastritis is positive for H. pylori. Thus, H. pylori-associated gastritis is theunderlying cause of almost all gastric diseases; hence, treatment of this gastritis throughbacterial eradication therapy is likely to prevent most gastric conditions, including gastriccancer.
4. Strategy to eliminate gastric cancer in JapanThe strategy to eliminate gastric cancer in Japan should be different for adolescents than for
elderly people. This is because bacterial eradication in adolescents achieves nearly 100%
prevention of gastric cancer, but the incidence of this cancer increases with age [21, 22].
The recommended strategy for adolescents is a test-and-treat approach, which includes H.

22

pylori testing of junior high school and high school students, followed by immediate H. pylori
eradication therapy for those with a positive result. Eradication in adolescents should be able
to prevent H. pylori-related diseases such as gastric ulcers and gastric polyps, as well as
preventing the development of nearly 100% of gastric cancers. It is estimated thatapproximately 5% of all teenagers in Japan are positive for H. pylori, suggesting that the costof this approach would not be so high. Some local governments have already scheduled free
H. pylori testing for junior high school students [23].
The recent expansion of health insurance coverage allows individuals with symptoms suchas gastric heaviness to present to a hospital for the diagnosis and treatment of H. pyloriassociated gastritis. For a patient to obtain health insurance coverage, endoscopy must be
performed first for the diagnosis of gastritis, and most patients seem to have chronic gastritis
by the time they undergo endoscopy. It is expected that many cases of gastric cancer will be
discovered during this endoscopic examination. This project thus includes a form ofendoscopic screening supported by medical insurance. All patients in whom gastritis isdiagnosed are supposed to receive H. pylori eradication therapy. In patients with obvious
atrophic gastritis, periodic endoscopic follow-up is recommended every 1 or 2 years evenafter eradication therapy, whereas patients with no or mild atrophy and those who are
negative for H. pylori infection can be followed up by optional screening instead of strategic
screening (Fig. 1.2.1) [24].
In Japan, the success rate of H. pylori eradication therapy is decreasing every year becauseof the increase in bacteria resistant to clarithromycin, but secondary eradication therapy withmetronidazole achieves a high success rate (> 95%). That may be because resistance tometronidazole is very low (about 5%) in Japan, where health insurance coverage foradministration of metronidazole is limited and its use remains uncommon [20].
Although it is not clear to what extent the use of eradication therapy in patients with H. pyloriassociated gastritis will inhibit the development of gastric cancer, a good model may be
peptic ulcers, for which H. pylori eradication therapy was first covered by the Japanesenational health scheme in 2000. Since then, the incidence of peptic ulcers has decreased
dramatically, by about 60% over 10 years. In addition, the medical costs of treating ulcers
have decreased by 47% during that period. Although it is unclear whether the results
obtained with gastric cancer will be comparable to those for peptic ulcers, H. pylori
eradication therapy (etiological treatment) for H. pylori-associated gastritis will lead to a longterm decrease of gastric cancer. Such treatment will inhibit the development of peptic ulcers
and gastric polyps as well as gastric cancer, suggesting a greater reduction of medical costs
than that achieved by providing insurance coverage for H. pylori eradication therapy inpatients with peptic ulcers [25].

23Fig. 1.2.1. Strategy to eliminate gastric cancer in Japan. Endoscopy must be performed first for the
diagnosis of gastritis to obtain health insurance coverage in Japan. This project might include a formof endoscopic screening supported by medical insurance. All patients in whom gastritis is diagnosed
are supposed to receive Helicobacter pylori eradication therapy. In patients with obvious atrophic
gastritis, periodic endoscopic follow-up is recommended every 1 or 2 years even after eradication
therapy. Source: Asaka et al. (2014) [24]. © Masahiro Asaka, Mototsugu Kato, Naoya Sakamoto,2013.

There are two potential outcomes of the gastric cancer elimination project suggested herewith regard to gastric cancer-related deaths in Japan. One is a definite decrease in theincidence of gastric cancer resulting from the widespread use of H. pylori eradication therapy(a direct effect of this therapy). The other is a decrease in the number of deaths resulting
from an increase in the diagnosis of early gastric cancer owing to mandatory endoscopy at
the time of presentation for chronic gastritis. The target would be to eventually increase theproportion of early gastric cancer from the current 60% to about 90%, which would make itpossible to increase the 5-year survival rate for gastric cancer patients in Japan toapproximately 90%. Because the baby boomer generation represents a huge population
turning 65 and entering the cancer-prone years, the number of deaths from gastric cancer islikely to increase by 2020 if no countermeasures are taken. In contrast, if the gastric cancer
elimination project is successful and about 50% of people with H. pylori infection receive
eradication therapy, the number of deaths from gastric cancer will decrease to about 30 000
in 2020 (Fig. 1.2.2) [24].

24Fig. 1.2.2. Anticipated gastric cancer deaths in Japan, with or without countermeasures. If the gastriccancer elimination project is successful and about 50% of people with Helicobacter pylori infection
receive eradication therapy, the number of deaths from gastric cancer will decrease to about 30 000
in 2020. Source: Asaka et al. (2014) [24]. © Masahiro Asaka, Mototsugu Kato, Naoya Sakamoto,2013.

Without
countermeasures
Joining gastric cancer
elimination programme

5. Conclusion
In February 2013, national health insurance coverage for H. pylori eradication therapy totreat H. pylori-associated chronic gastritis became available in Japan. H. pylori-associatedgastritis leads to development of gastric and duodenal ulcers and gastric polyps. Therefore,
providing treatment for gastritis is likely to substantially decrease the prevalence of both
gastric and duodenal ulcers and polyps. Because treatment for H. pylori-associated gastritis,which leads to atrophic gastritis and gastric cancer, is now covered by health insurance inJapan, a strategy to eliminate gastric cancer-related deaths by taking advantage of thisinnovation was planned. According to this strategy, patients with gastritis will be investigatedfor H. pylori infection and those who are positive will receive eradication therapy followed byperiodic surveillance. If this strategy is implemented, deaths from gastric cancer in Japan will
decrease dramatically after 10–20 years.

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2. Takeda Pharmaceutical Company (2013). Helicobacter pylori gastritis approved asadditional indication in Japan for Helicobacter pylori eradication by triple therapy with
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5. Kaneko E, Nakamura T, Umeda N, Fujino M, Niwa H (1977). Outcome of gastriccarcinoma detected by gastric mass survey in Japan. Gut. 18(8):626–30.
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(2001). Helicobacter pylori infection and the development of gastric cancer. N Engl J
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22. Asaka M, Kato M, Graham DY (2010). Strategy for eliminating gastric cancer in Japan.
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Introduction of an examination and treatment for Helicobacter pylori infection in highschool health screening. J Gastroenterol. 46(12):1353–60.
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27

Chapter 1.3
The regional status of current or planned gastric cancer prevention
strategies in Taiwan, China
Yi-Chia Lee
Given the promising results of the gastric cancer prevention programme on Matsu Island
over a 10-year follow-up period, the concept of this preventive strategy was disseminated tothe health-care authorities on the main island of Taiwan, China. Starting in 2012, aprevention programme using modified screening design and eligibility criteria was
implemented in a general population in Changhua County, Taiwan, China. This chapter
provides a detailed rationale for this community-based study, addressing the burden ofgastric cancer, design of the prevention programme, method of invitation to participants,
screening test, antibiotic treatment, endoscopic examination, evaluation method, and future
perspectives.
1. Gastric cancer burden in Taiwan, China
Gastric cancer was the seventh most common cancer in Taiwan, China in 2010 (sixth inmales and seventh in females). The median age of gastric cancer occurrence is about
70 years. The time trends are shown in Table 1.3.1. The absolute numbers of incident cases
and the incidence rates have increased gradually due to population ageing. The absolute
numbers of deaths and the mortality rates are almost constant. Therefore, gastric cancer
remains a significant public health burden in Taiwan, China.
Table 1.3.1. Time trends of gastric cancer in Taiwan, China for 1995–2010: number of people at risk,
number of incident cases, number of deaths, and incidence and mortality rates of gastric cancer per
100 000 population
Year

Population

New gastriccancer cases

Gastric cancer
deathsIncidence rate

Mortality rate

1995

21 358 297

2849

2262

13.34

10.59

1996

21 527 195

3078

2519

14.30

11.70

1997

21 741 711

3194

2348

14.69

10.80

1998

21 927 683

3291

2443

15.01

11.14

1999

22 092 394

3386

2360

15.33

10.68

2000

22 276 672

3352

2374

15.05

10.66

2001

22 405 568

3502

2446

15.63

10.92

2002

22 520 776

3692

2433

16.39

10.80

2003

22 604 550

3356

2349

14.85

10.39

2004

22 689 122

3681

2500

16.22

11.02

2005

22 770 383

3487

2490

15.31

10.94

2006

22 876 527

3674

2398

16.06

10.48

2007

22 958 360

3691

2474

16.08

10.78

2008

23 037 031

3636

2292

15.78

9.95

2009

23 119 772

3848

2282

16.64

9.87

2010

23 162 123

3854

2261

16.64

9.76

28

2. Rationale for gastric cancer prevention in Taiwan, China
For the intermediate-risk population (in which the incidence rate of gastric cancer is about
16.6 per 100 000 people per year), two major issues may determine the applicability ofgastric cancer prevention in Taiwan, China:
 When to screen?
 How to screen?
2.1 When to screen
The Matsu Island campaign against gastric cancer has suggested that the screen-and-treat
approach for Helicobacter pylori infection may be an effective strategy for primary prevention
in a high-risk population [1]. It is also known that, without previous opportunistic treatment,
the frequency and the severity of H. pylori-associated precancerous lesions increase withage. Furthermore, the use of non-steroidal anti-inflammatory drugs/aspirin is higher in theolder age range, which would be expected to have a synergistic effect with H. pylori infection
on the risk of peptic ulcers and/or bleeding. To increase the yield rate of endoscopy as a tool
for secondary prevention, it seemed reasonable to target the older population, in which theprevalence of latent H. pylori infection is lower and the burden of incident gastric pathology ishigher. Therefore, it was planned to screen the general older adult population aged 50–
69 years, in which the incidence rate of gastric cancer increases to about 30 per 100 000
person-years (Fig. 1.3.1). Those who were younger than 50 years would receive
opportunistic testing and treatment, which is now common clinical practice in Taiwan, China.
The other reason for screening the general older adult population was related to the delivery
system described below (Section 2.2).
2.2 How to screen
The candidate screening tests will likely include the 13C urea breath test (13C-UBT) and theH. pylori stool antigen test (HPSA) [2]. In Taiwan, China, starting in 2004, the government
initiated a mass screening programme for colorectal cancer (the leading incident cancer in
Taiwan, China) using biennial faecal occult blood testing with a faecal immunochemical test
(FIT) for the older adult population aged 50–69 years (extended to 50–74 years in June2013). Mass screening, including the processes of invitation, distribution of FIT, testing of
faecal sample, referral for colonoscopic examination, and histopathological diagnosis, were
performed step by step by the local public health units, clinics, and hospitals in eachmunicipality. All the screening results were transmitted via virtual private network to a central
database, which is used to periodically generate standardized indicators for the central andlocal governments to monitor the screening performance. This established delivery system
could serve as a strong basis for the implementation of a two-in-one, stool sample-based
test panel for both colorectal cancer and gastric cancer. Therefore, it is insightful to use
HPSA for mass screening. In addition to its easy incorporation into the established delivery
system, the advantages of HPSA include its convenience, lower price, and reduced
personnel needs.
3. Design of gastric cancer prevention programme in Changhua County, Taiwan,
China
Changhua County, which is located in central Taiwan, China (Fig. 1.3.1), has a population of
about 1 300 000. For the older adult population aged 50–69 years, the gastric cancer
incidence rate in 2009 was about 29 per 100 000 person-years, and the gastric cancer
mortality rate in 2011 was about 15 per 1000 000 person-years. In 2012, under the auspicesof the Changhua County Public Health Bureau, a proof-of-concept study was conducted in
Changhua County for gastric cancer prevention. For this population, HPSA was performed
for the first time, designed as a once-in-a-lifetime test, and appended to the Changhua
Community-based Integrated Screening programme [3]. This integrated screening
programme has provided oral inspection for oral/throat cancer, mammography for breast

29

cancer, Pap smear for cervical cancer, and FIT for colorectal cancer by annually inviting
10 000 people to be screened. Among these 10 000, eligible people were further invited toparticipate in the screening for gastric cancer. The flow chart is shown in Fig. 1.3.2.
Fig. 1.3.1. Gastric cancer incidence rates (per 100 000 population in 2009), mortality rates (per
100 000 population in 2011), and mortality-to-incidence ratio (or case fatality rate) in the population
aged 50–69 years in Taiwan, China. Numbers in parentheses represent the rankings of each city or
county.

30

Fig. 1.3.2. Flow chart of the community-based screening for and treatment of Helicobacter pylori
infection with the H. pylori stool antigen test (HPSA) in Changhua County in Taiwan, China (2013).
Note that anti-H. pylori treatment could be reimbursed by the National Health Insurance (NHI) when
13
13
active peptic ulcers were found by endoscopy. C -UBT, C-urea breath test; EGD,
esophagogastroduodenoscopy; FIT, faecal immunochemical test; GI, gastrointestinal; PPI, proton
pump inhibitor.

31

4. Invitation method
Before the new screening strategy was implemented, a series of consensus meetings andeducational programmes were held for primary care physicians and first-line health-care
workers. Beginning on 21 April 2012, eligible participants were invited by telephone or
postcard from 27 public health units covering a total of 26 townships in Changhua County(Fig. 1.3.3). A structured questionnaire was used to collect their medical and medication
histories.
Fig. 1.3.3. The geographical locations of 26 townships in Changhua County in Taiwan, China.

5. H. pylori stool antigen test
Two diagnostic accuracy studies for HPSA were performed before it was widely
implemented. The aims were: To evaluate the diagnostic accuracy of HPSA in identifying H. pylori infection.
 To evaluate the diagnostic accuracy of HPSA in detecting upper gastrointestinal
lesions/cancers.
First, to evaluate the accuracy of HPSA in diagnosing H. pylori infection, a hospital-based
study was conducted by recruiting 117 consecutive patients who were referred from the32primary care setting. These patients underwent two invasive tests (rapid urease test andhistology) and three non-invasive tests (13C-UBT, serology, and HPSA) for diagnosing H.
pylori infection. The reference standard for a positive H. pylori infection was defined as
positive results for at least two of the following three tests: 13C-UBT, rapid urease test, andhistology. The sensitivity and specificity of HPSA were estimated to be 88% and 99%,
respectively, by taking into account about 1% of cases with trace-line readings. The
specificity and positive predictive value of HPSA were significantly higher than those of theserological test. The second part of the same study consisted of a screening study based on
2720 participants, in which the concordance rate between the results of HPSA and 13C-UBT
was 91.7% and the kappa statistic was 0.78 [4].
Second, to evaluate the feasibility of combining HPSA with FIT and to determine thediagnostic accuracy in detecting upper and lower gastrointestinal tract lesions, a diagnostic
accuracy study was also performed. A total of 3172 participants were recruited to undergo
upper endoscopy and colonoscopy. The sensitivity and specificity of HPSA were 53% and81%, respectively, for detecting upper gastrointestinal lesions, 60% and 81%, respectively,
for detecting gastric lesions, and 78% and 76%, respectively, for detecting gastric cancer [5].
6. Antibiotic treatment
In 2012, individuals with positive HPSA results underwent endoscopic screening andantibiotic treatment, including: 7-day triple therapy (40 mg of esomeprazole once a day, 1 g of amoxicillin twice aday, and 500 mg of clarithromycin twice a day), and 10-day levofloxacin-based triple therapy (40 mg of esomeprazole once a day, 1 g ofamoxicillin twice a day, and 500 mg of levofloxacin once a day) for individuals inwhom initial treatment failed.
Based on experience from the Matsu Island gastric cancer prevention programme, theretest–retreatment practice was also included in this screening programme, with the hope of
reducing the risk of antibiotic-resistant strains of H. pylori. HPSA was performed 6–8 weeks
after the end of antibiotic treatment. For individuals whose test remained positive after two
courses of antibiotic treatment, no further empirical treatment was given. Instead, a third-line
treatment study was in progress, in which the optimal regimen was designed to overcome
antibiotic resistance on the basis of phenotypic resistance (minimum inhibitory
concentrations) and genotypic resistance (point mutations in the 23S ribosomal RNA andgyrase A genes).
In 2013, individuals with positive HPSA results would receive: 10-day sequential therapy (40 mg of esomeprazole and 1 g of amoxicillin twice a day
for days 1–5, followed by 30 mg of lansoprazole, 500 mg of clarithromycin, and
500 mg of metronidazole twice a day for days 6–10), and 10-day levofloxacin-based triple therapy (40 mg of esomeprazole once a day, 1 g ofamoxicillin twice a day, and 500 mg of levofloxacin once a day) for individuals inwhom initial treatment failed.
HPSA was performed 6–8 weeks after the end of antibiotic treatment. The purpose was totry to increase the first-line eradication rate. This evaluation is still in progress.
7. Phone call contact method
To increase the compliance with antibiotic treatment and evaluate the occurrence of sideeffects, a phone call contact method was designed. This concept was derived from directly
observed therapy for pulmonary tuberculosis, which remained an important public healthproblem in Taiwan, China. The first phone call contact would be made within 3 days after the33

start of treatment. During the course of treatment, there would be at least three phone callcontacts on different dates, and the results were recorded in a standardized questionnaire(Fig. 1.3.4). The method was applied to the 7-day triple therapy, 10-day sequential therapy,
and 10-day second-line therapy.
8. Endoscopy
Individuals with positive HPSA results were referred to 15 local gastrointestinal clinics and 9
hospitals in Changhua County for antibiotic treatment and/or endoscopic diagnoses. The
endoscopic diagnoses of gastrointestinal neoplasia were confirmed by histological results
under routine medical practice.
9. Evaluation method
Standard screening indicators, including the participation rate, positive rate, referral rate,
endoscopic findings, positive predictive value, and detection rate, were used to evaluate theapplicability of this screening strategy within the community. The mass screening was to be
conducted on an annual basis. The aims of the three successive rounds are as follows.
9.1 First round (2012–2013)
 To demonstrate proof of concept.
 To evaluate the eradication rate of a test–treat–retest–retreat strategy.
9.2 Second round (2013–2014)
 To optimize the efficacy of anti-H. pylori treatment.
 To establish the basis for a randomized trial to evaluate the efficacy of using thisscreening strategy.
9.3 Third round (2014–2015)
 To compare the eradication rate between the first round and the second round.
 To perform an economic modelling study to simulate the long-term outcome.
 To evaluate the reinfection rate of H. pylori after eradication.
 To launch a community-based randomized trial of screening and treating H. pylori
infection integrated with colorectal cancer screening with the faecal occult blood test.
10. Results
10.1 First round (2012–2013)
A total of 6798 people aged 50–69 years were evaluated, of which 3621 eligible people wereinvited to participate. Among them, 941 (26%) were male and the mean age was 57.9 years.
A total of 3454 (95.4%) participants returned an adequate stool test sample, and 1251
samples had positive HPSA results. Among the participants with positive results, 817(65.3%) were referred to clinics or hospitals, 755 (92.4%) received antibiotic treatment, and643 (78.7%) underwent upper endoscopic examination. Significant upper gastrointestinal
lesions were found in 205 people (31.9%), including 7 erosive oesophagitis (grade C or D), 1
Barrett oesophagus, 4 oesophageal varices (form II or III), 189 peptic ulcers, and 2 gastriccancers. The positive predictive value was 31.9%, the detection rate for significant uppergastrointestinal lesions was 5.9% (205 of 3454), and the number of endoscopies required tofind one gastric cancer was 322 [5]. The eradication rate of first-line treatment wasapproximately 88%.

34

Fig. 1.3.4. Questionnaire of the phone call contact method to improve the compliance and evaluate
the side-effects related to anti-Helicobacter pylori treatment in Changhua County in Taiwan, China.

Questionnaire of the compliance and side effects to antibiotic
treatment using the phone call contact method
Basic data of screenee:
Name

Study ID

Birthday

Gender

Telephone

Mobile phone

Treatment data:
Course of treatment

First
contact

Secondcontact

Third
contact

Starting dateEnding date

Date

Compliance

Allergic
reaction

Nauseaorvomiting

Headacheordizziness

Epigastricdiscomfort

Diarrhoea

OthersManagement ofside-effect

Date

Compliance

Allergic
reaction

Nauseaorvomiting

Headacheordizziness

Epigastricdiscomfort

Diarrhoea

OthersManagement ofside-effect

Date

Compliance

Allergic
reaction

Nauseaorvomiting

Headacheordizziness

Epigastricdiscomfort

Diarrhoea

OthersManagement ofside-effectName of Public Health Unit: _______________Name of phone call contact personnel: _________________

35

10.2 Second round (2013–2014)
In 2013, 4009 eligible people were invited to participate. Among them, 1624 (40.5%) weremale and 1325 (33.1%) tested positive for H. pylori. Patient referrals, endoscopies, andantibiotic treatment are under way. Preliminary results showed that 883 (66.6%) participants
were referred for endoscopy and/or antibiotic treatment. A total of 877 (99.3%) people
received antibiotic treatment. Among 647 (73.3%) individuals who also underwent
endoscopy, 3 gastric cancers were found, and the number of endoscopies required to find
one gastric cancer was 216.
11. Conclusion
Based on the experience from Matsu Island, a pilot study targeting the older adult population
aged 50–69 years was conducted in Changhua County in Taiwan, China. Under theframework of the colorectal cancer screening programme, HPSA testing was performed with
FIT for simultaneous detection of upper and lower gastrointestinal lesions. Both primaryprevention (anti-H. pylori treatment) and secondary prevention (endoscopic screening) were
implemented for gastric cancer. Preliminary results showed that this strategy was applicableand effective in detecting gastric cancer. Participants benefited from antibiotic treatment for
peptic ulcer and chronic gastritis, and chemoprevention for gastric cancer. In 2012, anothercounty in Taiwan, China (Yilan County) voluntarily adopted this screening strategy under the
auspices of the local government. Using the pilot studies as the basis, a randomized
community-based trial is in progress (NCT01741363).

References
1. Lee YC, Chen TH, Chiu HM, Shun CT, Chiang H, Liu TY, et al. (2013). The benefit ofmass eradication of Helicobacter pylori infection: a community-based study of gastriccancer prevention. Gut. 62(5):676–82. http://dx.doi.org/10.1136/gutjnl-2012-302240
PMID:22698649
2. Malfertheiner P, Megraud F, O’Morain CA, Atherton J, Axon ATR, Bazzoli F, et al.;European Helicobacter Study Group (2012). Management of Helicobacter pylori
infection–the Maastricht IV/Florence Consensus Report. Gut. 61(5):646–64.
http://dx.doi.org/10.1136/gutjnl-2012-302084 PMID:22491499
3. Yeh YP, Hu TH, Cho PY, Chen HH, Yen AMF, Chen SLS, et al.; Changhua CommunityBased Abdominal Ultrasonography Screening Group (2014). Evaluation of abdominal
ultrasonography mass screening for hepatocellular carcinoma in Taiwan. Hepatology.
59(5):1840–9. http://dx.doi.org/10.1002/hep.26703 PMID:24002724
4. Lee YC, Tseng PH, Liou JM, Chen MJ, Chen CC, Tu CH, et al. (2014). Performance of aone-step fecal sample-based test for diagnosis of Helicobacter pylori infection in primarycare and mass screening settings. J Formos Med Assoc. [Epub ahead of print]
http://dx.doi.org/10.1016/j.jfma.2012.05.014
5. Lee YC, Chiu HM, Chiang TH, Yen AMF, Chiu SYH, Chen SLS, et al. (2013). Accuracy of
faecal occult blood test and Helicobacter pylori stool antigen test for detection of uppergastrointestinal lesions. BMJ Open. 3(10):e003989. http://dx.doi.org/10.1136/bmjopen2013-003989 PMID:24176798

36

Chapter 1.4
The regional status of current or planned gastric cancer prevention
strategies in Latin America
Catterina Ferreccio
Gastric cancer mortality rates are extremely high in some Latin American countries, such as
Chile, Costa Rica, and Colombia, whereas the rates are low in other countries, like Mexicoand Argentina the rates. Nevertheless, even in Mexico and Argentina there are areas orcommunities with high rates of gastric cancer, like Chiapas and southern Argentina,
respectively.
1. Gastric cancer prevention in Latin America
Gastric cancer is an important health problem for most Latin American countries, yet nonational programmes for the primary prevention of gastric cancer have been implemented orplanned. In the area of secondary prevention of gastric cancer, the only Latin Americancountry with a national programme is Chile, with its AUGE (Acceso Universal con Garantías
Explícitas; Universal Access with Explicit Guarantees) plan. This programme guarantees
endoscopic examination including Helicobacter pylori detection, biopsy, and treatment for
symptomatic adults aged 40 years and older. Most activities for the secondary prevention ofgastric cancer in Latin American countries have been conducted by private organizations
and have been based on the detection of gastric cancer through endoscopy. These
opportunistic programmes had subnational coverage (mostly local or regional) and lasted a
few years or decades. Colombia, Mexico, and Paraguay have made efforts to develop a
consensus on the histopathology of gastric cancer precursor lesions; nevertheless, thisinformation has not yet been included in prevention programmes.
Practically all Latin American countries have coexisting populations with high and low risk ofdeveloping gastric cancer. These areas not only show differences in incidence and mortality
but also show differences in the clinical and epidemiological characteristics of gastric cancer[1, 2]. Populations with high risk of gastric cancer are typically of low socioeconomic status
and have high H. pylori prevalence; the high levels of H. pylori are reached at younger ages
[3, 4]. In high-risk areas, gastric cancer is mainly of the intestinal type, is well differentiated,
initiates in the distal part of the stomach, and is diagnosed at an advanced stage, and thus
has a poor prognosis (5-year survival < 10%) [5]. In contrast, areas where risk of gastriccancer is low are the most affluent in each country and region and have low prevalence of H.
pylori, most noticeably in younger generations [3]; patients present at early stages, havegreater access to endoscopies and biopsies, and possibly have higher survival rates. In lowrisk areas, gastric cancer tends to be located in the proximal part of the stomach, is lessdifferentiated, affects younger patients, and is less associated with H. pylori [6]. In both highand low-risk areas, men are affected more frequently than women, but the sex differential
decreases in low-risk areas.
The current understanding is that H. pylori infection is the driving force for gastric cancer,
especially in high-risk areas, and that in theory gastric cancer can be largely prevented.
Prevention strategies in some countries include mass screening of the adult population or
endoscopic examination of symptomatic individuals. For instance, Japan introduced
screening in the 1960s and currently coverage is estimated at 30%; the programme is basedon barium double-contrast radiography followed by endoscopy of suspicious images. This
strategy has not been adopted in other countries as a nationwide strategy due to its highcost, the requirement of trained endoscopists and pathologists, its invasiveness, and the37uncertainties about its effectiveness [7]. Several authors have proposed shifting fromsecondary to primary prevention of gastric cancer based on H. pylori test-and-treat
strategies [8, 9]. In Latin American countries, there are no national programmes for the
primary prevention of gastric cancer [10]. This chapter reviews the gastric cancer prevention
strategies that the governments and ministries of health in Latin American countries currently
offer.
2. Gastric cancer prevention strategies by country
2.1 Argentina
In some areas of southern Argentina, gastric cancer mortality rates per 100 000 population
reach 32 in men and 8 in women, whereas in Buenos Aires the corresponding rates are 8
and 3 [6]. Argentina does not have a national screening programme for gastric cancer or
national guidelines for its management. The current programmes and management
guidelines are limited to cervical, breast, skin, prostate, ovarian, lung, and paediatric cancers(http://www.msal.gov.ar/inc/index.php).
2.2 Belize
In Belize, there is a decreasing trend in gastric cancer mortality, with rates near 6 per
100 000 population and higher in men (6.2) than in women (1.0). There are no prevention
programmes for gastric cancer; the only prevention programme is cervical cancer screening
based on the Pap test [10].
2.3 Bolivia
The cancer prevention programme in Bolivia is in the early development stages and focuseson early detection of cervical cancer with Pap smears, covering about 12% of the population,and early detection of breast cancer with self-examination followed by clinical examinationand mammography. Gastric cancer prevention is not included in the programme [10].
2.4 Brazil
In Brazil, as a general strategy for all cancers, prevention is focused on improving lifestylefactors(diet,
tobaccouse,
alcoholconsumption,
physical
activity)(http://www2.inca.gov.br/wps/wcm/connect/tiposdecancer/site/home/estomago/prevencao).
Early detection programmes are offered for only cervical and breast cancers [10].
2.5 Chile
In Chile, the burden of gastric cancer is high, with mortality rates per 100 000 of 25.1 in men
and 12.5 in women [11]. Gastric cancer prevention has been addressed by private andpublic initiatives. The first experience with mass endoscopic screening was conducted by
Llorens from 1978 to 1986 in 42 492 individuals in Santiago [12], with support from theJapanese government. Llorens found a gastric cancer prevalence of 0.4% and 1.3% among
asymptomatic and symptomatic subjects, respectively; in these groups, the percentages ofgastric cancer at early stages were 15% and 11%, respectively. In 1995, the Ministry of
Health of Chile conducted an endoscopic-based screening pilot programme in Santiago; thefirst 10-year (1996–2006) performance of this project was recently evaluated. Theintervention area had a population of 223 708; 10 284 individuals (13 268 exams) werescreened (~4.6 individuals per 1000 population per year), and 190 gastric cancer cases (8.5
per 100 000 population per year) were identified, of which 32.1% were at early stages(58.7% in women, 27.6% in men). The endoscopy detection rate was 1.4% (0.7% for men,
3.3% for women). It was estimated that 70 gastroscopies were required to identify one
gastric cancer. The specific 5-year survival rate was 40% (53.2% in women, 33.3% in men)[13]. In 2006, the Ministry of Health initiated a nationwide gastric cancer detection
programme, which is opportunistic and focuses on symptomatic individuals; it guarantees

38

endoscopic examination for any patient who fulfils some of the following criteria: individuals
older than 40 years with epigastric pain lasting more than 15 days, heavy bleeding, anaemia,
or weight loss of unknown origin, sensation of full stomach after eating, general feeling of
weakness, tiredness, loss of appetite, dysphagia, history of gastrectomy more than 15 years
earlier, and immediate family member with gastric cancer. H. pylori eradication isrecommended “in any patient undergoing endoscopy, unless endoscopic examination isnormal or the stomach mucosa presents only superficial and minimal lesions; eradication is
also recommended in patients with duodenal or stomach ulcers, atrophic gastritis,
lymphoma, adenoma, gastric cancer, and family history of gastric cancer”. The
recommended H. pylori eradication scheme is 500 mg of clarithromycin plus 1 g ofamoxicillin plus 20 mg of omeprazole, all taken twice a day for 7 days [14].
2.6 Colombia
The gastric cancer mortality rate in Colombia is one of the highest in Latin America, withareas of high risk in the Andes Mountains and areas of low risk at the coast [15]. Colombia
has an ambitious programme for cancer control, the Colombia National Cancer Control
Program 2012–2020. The primary prevention goals, as in most other Latin Americancountries, are to reduce the prevalence of modifiable risk factors for cancer (tobacco use,
physical inactivity, and unhealthy diet). The programme also addresses other factors, suchas alcohol consumption and ultraviolet exposure, and includes human papillomavirus (HPV)
vaccination; in addition, it seeks to reduce occupational oncogenic exposures to asbestos,silica, benzene, lead, and ionizing radiation. The programme for early detection is currently
limited to cervical and breast cancers. There are no specific gastric cancer prevention
strategies [10]. Investigators in Colombia, Mexico, and Paraguay have studied the
reproducibility of the histopathology of gastric cancer precursor lesions, which could form thebasis for a future Latin American consensus [16].
2.7 Costa Rica
Costa Rica also has one of the highest gastric cancer mortality rates in the region; gastriccancer occupies the second place among the main causes of cancer death in men andwomen [10]. The National Plan for Cancer Prevention and Control 2011–2017 includes,
among the primary prevention measures, the control of lifestyle-related risk factors and ofchemical exposures. The programme for early detection includes only cervical and breast
cancers. There is no mention of any specific measure to prevent gastric cancer [17]. There
was an initiative in 1995, supported by the Japanese government, in the high-risk area of
Cartago, where the Centro de Detección de Cáncer Gástrico del Hospital Max Peralta
initiated an endoscopy-based early detection programme for gastric cancer, following theJapanese model of X-ray screening, video endoscopy, and stomach biopsy. The programme
included 6828 individuals, of whom 34% required endoscopy; 59 (0.86%) gastric cancer
cases were identified, 55% of which were detected at early stages. The second round ofscreening, 2 years later, included 5046 participants, and 28 (0.55%) gastric cancer cases
were identified; 80% of cases were at early stages. The 5-year gastric cancer survival rate
was 85%, with an estimated reduction of 50% in gastric cancer mortality. Nevertheless, thisprogramme was considered inapplicable to the country due to its high cost [18].
2.8 Cuba
Gastric cancer mortality rates in Cuba are relatively low in both men and women (7.2 and 3.6
per 100 000, respectively). Gastric cancer is the fifth most common cause of cancer death inmen and is not among the 10 most common causes in women. Cuba has a national
population cancer registry. Existing screening programmes cover cervical, breast, and coloncancers [10].

392.9 Dominican Republic
In the Dominican Republic, gastric cancer is the fifth most common cause of cancer death inmen and is not among the 10 most common causes in women. Screening programmes exist
for cervical and breast cancers [10].
2.10 Ecuador
A high-risk area for gastric cancer, Ecuador does not have a national gastric cancer
prevention programme. There is a national programme for cervical cancer, which is provided
by SOLCA (Sociedad de Lucha Contra el Cáncer del Ecuador), a non-profit nationalorganization with representatives in most large cities in the country; they provide clinicalguidelines for gastric cancer (http://www.solca.med.ec/).
2.11 El Salvador
In El Salvador, gastric cancer is the leading cause of cancer death in both men and women,with mortality rates per 100 000 of 17.2 in men and 12.3 in women. The only prevention
programmes are for cervical and breast cancers.
2.12 Guatemala
Similarly to El Salvador, in Guatemala gastric cancer is the leading cause of cancer death inboth men and women, representing 20% of all cancer deaths. The only screening
programme is focused on cervical cancer.
2.13 Honduras
Honduras is also a high-risk country for gastric cancer, which is the leading cause of cancer
death in men and the second most common cause in women [10]. Honduras does not havea specific gastric cancer prevention programme. The Ministry of Health issued a National
Strategic Plan for the Prevention and Control of Cancer 2009–2013, which is limited to early
detection and primary prevention of cervical cancer [19].
2.14 Mexico
Overall, Mexico has one of the lowest risks of gastric cancer of Latin American countries;
nevertheless, it has areas like Chiapas, where gastric cancer mortality is twice the country’s
overall rate (8.0 and 3.9 per 100 000, respectively) [20]. The cancer priorities for 2007–2012
include screening for only cervical and breast cancers [21]. There is no mention of gastriccancer prevention in the package of guaranteed prevention and promotion services, which
promotes healthy diet and seeks to control obesity and tobacco use; this package covers
prevention of breast, cervical, and prostate cancers [22]. According to the Pan American
Health Organization, Mexico offers colorectal cancer screening [10].
2.15 Nicaragua
Nicaragua has an intermediate risk of gastric cancer, with mortality rates per 100 000 of 12.9
in men and 8.0 in women. The only screening programme is focused on cervical cancer [10].
2.16 Panama
Gastric cancer mortality rates in Panama are similar to those in Nicaragua, with mortality
rates per 100 000 of 13.1 in men and 7.4 in women. Panama has areas of high gastriccancer risk but does not have any specific intervention to prevent gastric cancer, althoughendoscopy is covered by the government as part of a medical workup. There are prevention
programmes for cervical and breast cancers [10].

402.17 Paraguay
The only cancer prevention programmes in Paraguay are cervical cancer screening basedon the Pap test and breast cancer screening based on self-examination.
2.18 Peru
A national programme exists for cervical cancer and breast cancer. With support from theJapanese government, Peru implemented esophagogastroduodenoscopy in 31 446
symptomatic patients between 1985 and 2002; gastric cancer prevalence was 3.19% in1988 and 0.92% in 2002 [23]. In 2013, the “Plan Esperanza” (Hope Plan) was launched toprioritize
thepreventionofbreast,cervical,andcoloncancers(ftp://ftp2.minsa.gob.pe/normaslegales/2012/DS009_2012_SA_EP.pdf).
In
this
plan,
endoscopy is offered to patients with high suspicion of digestive cancer. There is a medical
guide for gastric cancer, but it does not include prevention [24]. The PEAS (Plan Esencial deAseguramiento en Salud; Health Insurance Essential Plan) covers the diagnosis of gastriccancer by funding one endoscopy and one biopsy [25]. The decree regarding cancer for theperiod 2012–2015 includes cervical, breast, and colon cancers in the area of early detection;
gastric cancer is mentioned only in the diagnosis and treatment sections [26].
2.19 Puerto Rico
With low mortality rates for gastric cancer in both men and women (5.5 and 2.3 per 100 000,
respectively), Puerto Rico does not have a prevention programme focused on gastriccancer. Screening programmes exist for breast, cervical, and colorectal cancers [10].
2.20 Suriname
In Suriname, gastric cancer mortality rates are very low in both men and women (4.0 and 1.7
per 100 000, respectively). The only screening programme is focused on cervical cancer[10].
2.21 Trinidad and Tobago
Gastric cancer mortality rates are low in Trinidad and Tobago in both men and women (7.5
and 3.0 per 100 000, respectively). The only screening programme is focused on cervicalcancer [10].
2.22 Uruguay
Uruguay is a low-risk area for gastric cancer, and no intervention directed to prevent gastriccancer exists. The national cancer prevention programmes include early detection of breast,
cervical, and colon cancers [10].
2.23 Venezuela
Venezuela has areas with high risk of gastric cancer, like the state of Táchira, but does nothave a national intervention directed towards this cancer. From 1980 to 1989, a screening
programme was conducted in this high-risk region, with the collaboration of the Japanese
government. It was aimed at the population aged 35 years and older and was based on sixfilm indirect photofluorography using double contrast, to be repeated every1–2 years. During
this period, 114 000 examinations were performed, identifying 445 cases of gastric cancer[27]. This programme was not extended to other regions and has now been discontinued;
however, an endoscopic centre for early detection, diagnosis, and treatment of digestivecancers is maintained. The Venezuela Ministry of Health’s cancer control programme has
four specific components: cervical cancer screening based on the Pap test, breast cancer
screening based on self-examination, prostate cancer screening based on digital exam ofthe prostate and prostate-specific antigen (PSA) testing, and cancer registry development;
gastric cancer is not included [28].

41References
1. Heise K, Bertran E, Andia ME, Ferreccio C (2009). Incidence and survival of stomach
cancer in a high-risk population of Chile. World J Gastroenterol. 15(15):1854–62.
http://dx.doi.org/10.3748/wjg.15.1854 PMID:19370783
2. Torres J, Correa P, Ferreccio C, Hernandez-Suarez G, Herrero R, Cavazza-Porro M, etal. (2013). Gastric cancer incidence and mortality is associated with altitude in themountainous regions of Pacific Latin America. Cancer Causes Control. 24(2):249–56.
http://dx.doi.org/10.1007/s10552-012-0114-8 PMID:23224271
3. Ferreccio C, Rollán A, Harris PR, Serrano C, Gederlini A, Margozzini P, et al. (2007).
Gastric cancer is related to early Helicobacter pylori infection in a high-prevalencecountry. Cancer Epidemiol Biomarkers Prev. 16(4):662–7.
http://dx.doi.org/10.1158/1055-9965.EPI-06-0514 PMID:17416755
4. Queiroz DM, Harris PR, Sanderson IR, Windle HJ, Walker MM, Rocha AM, et al. (2013).
Iron status and Helicobacter pylori infection in symptomatic children: an international
multi-centered study. PLoS One. 8(7):e68833.
http://dx.doi.org/10.1371/journal.pone.0068833 PMID:23861946
5. de Martel C, Forman D, Plummer M (2013). Gastric cancer: epidemiology and risk factors.
Gastroenterol Clin North Am. 42(2):219–40. http://dx.doi.org/10.1016/j.gtc.2013.01.003
PMID:23639638
6. Galindo F (2009). Carcinoma gástrico. In: Galindo F. Cirugia digestiva. II-223, pp 1–31.
Available from: http://www.sacd.org.ar/dveintitres.pdf
7. Leung WK, Wu MS, Kakugawa Y, Kim JJ, Yeoh KG, Goh KL, et al.; Asia Pacific Working
Group on Gastric Cancer (2008). Screening for gastric cancer in Asia: current evidence
and practice. Lancet Oncol. 9(3):279–87. http://dx.doi.org/10.1016/S14702045(08)70072-X PMID:18308253
8. Kato M, Asaka M (2012). Recent development of gastric cancer prevention. Jpn J Clin
Oncol. 42(11):987–94. http://dx.doi.org/10.1093/jjco/hys151 PMID:23018579
9. Choi IJ (2013). Current evidence of effects of Helicobacter pylori eradication on preventionof gastric cancer. Korean J Intern Med. 28(5):525–37.
http://dx.doi.org/10.3904/kjim.2013.28.5.525 PMID:24009446
10. Pan American Health Organization (PAHO) (2013). Cancer in the Americas: country
profiles, 2013. Washington, DC: PAHO. Available from:http://www.uicc.org/sites/default/files/private/Cancer-Country-Profiles-2013-ENG.pdf
11. Ministerio de Salud (2012). Serie de defunciones por tumores malignos según sexo,
Chile 2001-2011. Santiago, Chile: Minsal. Available from: http://www.deis.cl/?p=2543
12. Llorens P (1991). Gastric cancer mass survey in Chile. Semin Surg Oncol. 7(6):339–43.
http://dx.doi.org/10.1002/ssu.2980070604 PMID:1759081
13. Galleguillos B (2013). Evaluación de 10 años de un programa de detección precoz decáncer gástrico: La Florida - Chile, 1996–2006 [Dissertation]. Santiago, Chile: Facultad
de Medicina, Pontificia Universidad Católica de Chile.
14. Ministerio de Salud (2010). Guía clínica: cáncer gástrico. Santiago, Chile: Minsal.
Available from: http://www.supersalud.gob.cl/difusion/572/articles-651_guia_clinica.pdf
15. Correa P, Cuello C, Duque E, Burbano LC, Garcia FT, Bolanos O, et al. (1976). Gastriccancer in Colombia. III. Natural history of precursor lesions. J Natl Cancer Inst.
57(5):1027–35. PMID:1003539
16. Kasamatsu E, Bravo LE, Bravo JC, Aguirre-García J, Flores-Luna L, Nunes-Velloso
MdelC, et al. (2010). Reproducibility of histopathologic diagnosis of precursor lesions ofgastric carcinoma in three Latin American countries. [Article in Spanish] Salud Publica
Mex. 52(5):386–90. http://dx.doi.org/10.1590/S0036-36342010000500005
PMID:21031244
17. Ministerio de Salud (2012). Plan nacional para la prevención y control del cáncer, 2011–2017. San José, Costa Rica: Ministerio de Salud. Available from:42http://www.ministeriodesalud.go.cr/gestores_en_salud/consejo_nacional_cancer/DM_pla
n_nacional_para_la_prevencion_y_control_del_cancer.pdf
18. Rosero-Bixby L, Sierra R (2007). X-ray screening seems to reduce gastric cancer
mortality by half in a community-controlled trial in Costa Rica. Br J Cancer. 97(7):837–43.
http://dx.doi.org/10.1038/sj.bjc.6603729 PMID:17912238
19. Secretaría de Salud, Honduras. Plan estratégico nacional para la prevención y control
del cáncer, 2009–2013. Available from:http://www.paho.org/hon/index.php?option=com_docman&task=doc_download&gid=126&Ite
mid=211
20. SINAIS/SINAVE/DGE/SALUD (2011). Perfil epidemiológico de los tumores malignos en
México. Available from:http://www.epidemiologia.salud.gob.mx/doctos/infoepid/publicaciones/2011/monografias/
P_EPI_DE_LOS_TUMORES_MALIGNOS_M%C3%A9xico.pdf
21. Secretaría de Salud, México. Programa de acción específico, 2007–2012. Available
from: http://www.spps.gob.mx/programas-y-proyectos.html
22. Secretaría de Salud, México (2007). Paquete garantizado de servicios de promoción yprevención. In: Estrategia nacional de promoción y prevención para el mejor salud.
Available from:http://www.promocion.salud.gob.mx/dgps/descargas1/estrategia_nacional.pdf
23. Ramírez Ramos A, Sánchez Sánchez R (2009). Latin American contribution to the studyof Helicobacter pylori. [Article in Spanish] Acta Gastroenterol Latinoam. 39(3):197–218.
PMID:19845260
24. Ministerio de Salud, Instituto Nacional de Enfermedades Neoplásicas (2011). Guía depráctica clínica: cáncer gástrico. Lima, Peru: Ministerio de Salud, Instituto Nacional deEnfermedades Neoplásicas. Available from:http://www.inen.sld.pe/portal/documentos/pdf/normas_tecnicas/2011/25042011_C_GASTRI
CO.pdf
25. Ministerio de Salud (2009). Plan esencial de aseguramiento en salud. Lima, Peru:
Ministerio de Salud. Available from:http://www.minsa.gob.pe/portada/aseguramiento/archivo/PEAS.pdf
26. Decreto supremo Nª 009-2012-SA (Executive Order N° 009-2012-SA). Cancer
comprehensive health care and improvement of access to oncology services in Peru are
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27. Pisani P, Oliver WE, Parkin DM, Alvarez N, Vivas J (1994). Case-control study of gastriccancer screening in Venezuela. Br J Cancer. 69(6):1102–5.
http://dx.doi.org/10.1038/bjc.1994.216 PMID:8198977
28. Capote Negrín LG (2013). Perfil epidemiológico y control del cáncer en Venezuela. Gac
Med Caracas. 121(1):43–52.

43

Chapter 1.5
The regional status of current or planned gastric cancer prevention
strategies in Europe
Mārcis Leja
There are two major sets of guidelines addressing gastric cancer prevention strategies in
Europe: the Maastricht IV guidelines on the management of Helicobacter pylori infection [1]and the MAPS (Management of precancerous conditions and lesions in the stomach)guidelines [2]. Both of these emphasize the need for gastric cancer risk stratification andpropose strategies to decrease the burden of gastric cancer.
However, the guideline statements have been only partially taken up by clinical practice.
Although mass eradication (“search-and-treat”) in areas of high gastric cancer risk has beensuggested by guidelines in Asia [3] and in Europe [1] and recent meta-analyses haveconfirmed the potential cost–effectiveness of this approach [4, 5], none of the high-riskcountries in Europe has accepted this approach, because of the potential adverse events,
including microbial resistance. Even though guidelines suggest pepsinogen detection as thebest available approach for non-invasive selection of the group for further diagnostic workup[1–3], so far there are not sufficient data on the potential of these tests to decrease mortality
due to gastric cancer to recommend their use in organized cancer screening programmes, atleast in Europe and in Caucasian populations.
This chapter presents a summary of major gastric cancer prevention studies and gives
insight into current and planned developments in the field. By considering the presence of
Caucasian populations outside the geographical region of Europe, this review will also cover
the activities in neighbouring territories, i.e. the Siberian part of the Russian Federation as
well as Kazakhstan.
1. Improvements in endoscopy
There are substantial differences between the routinely performed upper endoscopies in the
Far East (in particular, in Japan and the Republic of Korea) and in Europe and North
America.
In Japan, detailed endoscopic evaluation with multiple photo-fixations following well-defined
standards is the everyday practice. In Europe and North America, the standard biopsy
strategy with five non-targeted biopsies according to the updated Sydney system is therecommendation if no visually detectable lesions are present (although this recommendation
is frequently not followed in the community practice). The current guidelines do notrecommend limiting the biopsy sampling to locations where visually detectable lesions canbe identified, because of insufficient accuracy reported in previous studies [2]. However, thetechnologies are improving, and the targeted biopsy strategy is becoming more and more
attractive. The current state of knowledge about identification of stomach lesions with the
new visualization technologies has been reviewed recently [6].
Two (post-MAPS) studies to evaluate the possibilities of targeted biopsies with highresolution endoscopy have recently been started in Europe: one with the narrow-band
imaging (NBI) system by Olympus (principal investigator, M. Dinis-Ribeiro) and the otherwith the flexible spectral imaging colour enhancement (FICE) system by Fujifilm (principal
investigator, I. Kikuste). The protocol of the NBI study is designed as a multicentre
investigation, whereas the FICE study will be based in one centre or a few centres.

44

Several studies, including those mentioned here, will address the rationale for thesurveillance intervals as suggested by the MAPS guidelines.
2. Histological risk stratifications
There are minor discrepancies present within the current guidelines with respect to theapproach to biopsy sampling from a stomach mucosa without any visually detectablelesions: whereas traditionally, the updated Sydney classification requires a biopsy from theincisura of the stomach, the MAPS guidelines do not include this as part of the minimum
requirements. Two studies are close to being completed and published: one being
conducted in Magdeburg, Germany, and the other in Riga, Latvia. The preliminary resultsfavour the use of the incisura biopsies. The remaining open issues are deciding whether
subtyping of intestinal metaplasia and separate analysis of biopsies obtained from the major
and minor curvature are rational.
New staging systems for gastric premalignant lesions – OLGA and OLGIM – have beensuggested to simplify the clinical approach while using the same biopsy workup as for the
Sydney system (i.e. five biopsies, including the incisura angularis). The Operative Link on
Gastritis Assessment (OLGA) staging system is based on severity of atrophic gastritis,whereas the OLGIM system emphasizes the importance of intestinal metaplasia. The initially
proposed OLGA system is based on pooling the atrophy scores in each part of the stomach
into a simple OLGA stage, ranging from 0 to IV [7]. Because inter-observer agreement isbetter for intestinal metaplasia than for atrophy, the OLGIM system uses the same approach
but stages intestinal metaplasia instead of atrophy [8].
The stage by itself does not allow a judgement to be made about the topography of thelesion revealed (in particular, for the lower stages), but it is considered to be linked to theissues of prognosis and management, since most of the cancer cases are expected to be
associated with OLGA stages III and IV [9]. Such a stage distribution is also convenient for
research purposes [10].
Several recent studies have evaluated the rationale for the staging systems and found them
to be helpful in general. However, for the true validation of the systems, it is essential toconduct studies in high-risk areas demonstrating that cancer and dysplasia cases areassociated with the advanced stages (III/IV) but not the early stages. Few such studies are
currently under way.
A study in progress in the south of the Russian Federation (Stavropol and Cherkessk;
coordinating investigator, V. Pasechnikov; principal investigator, S. Kotelevets) is recruiting
patients referred for upper endoscopy and assessing them according to the OLGA staging
system as well as pepsinogen testing (using the Biohit system). The initial patient sample
includes 2965 individuals of Caucasian origin, with mean age 54 years (range, 18–92 years),
38.7% male patients, and H. pylori prevalence 74.7%. Decreased pepsinogen levels(decreased ratio of pepsinogen I to pepsinogen II; PgI/II < 3) have been found to correlate
well with advanced OLGA stages (V. Pasechnikov, personal communication).
An additional follow-up study is being conducted in Latvia to access the endoscopy andpathology (OLGA/OLGIM) results in patients with decreased pepsinogen levels (the initialstudy is described elsewhere [11] and is briefly characterized in the text below). Individuals
with decreased pepsinogen levels at study inclusion are invited for upper endoscopy with anappropriate biopsy workup. The results are expected by the end of 2014; the initial results
suggest that high-risk lesions may be distributed in different OLGA/OLGIM stages, notlimited to advanced stages.

45

3. Blood-sample-based gastric atrophy detection and its limitations
The traditional blood-sample-based (plasma or serum) indirect atrophy detection is based on
pepsinogen measurement. A decreased PgI level – more precisely, a decreased PgI/II ratio– indirectly reflects the lower functional activity and, therefore, indirectly also the presence ofatrophy in the stomach. Although previously reported [12] sensitivity results of pepsinogenlevels for gastric cancer identification could be considered acceptable in screening settings,
worse performance is reported in many of the studies. The results are better for detection ofatrophy, i.e. sensitivity of 66.7–84.6% and specificity of 73.5–87.1% [13–16], but significantly
lower sensitivity for detection of gastric cancer using the same cut-off values (36.8–62.3%)
has been reported [17–19]. This would potentially result in missing half, or even more thanhalf, of gastric cancer cases in settings of population-based screening.
Pepsinogen detection has been studied in Japan for decades; in Europe, the detection of
pepsinogens has become available more recently. Different methods and different cut-off
values have been used to define decreased circulating pepsinogen levels. Whereas a latex
agglutination method (in a conventional clinical chemistry analyser) is used in most of therecent studies in Japan, enzyme-linked immunosorbent assay (ELISA) is the most common
method in Europe and other parts of the world outside Japan. Although a relatively goodcorrelation has been reported between the results obtained with these two methods, theabsolute values differ; therefore, the results in absolute values cannot be translated between
the different studies unless identical test systems are used in similar study populations [20].
Therefore, regional validation of the test system is absolutely essential.
More recently, an additional marker – amidated gastrin-17 (G-17) – has been suggested tocharacterize atrophy in the antral part of the stomach; G-17 is secreted exclusively by the Gcells in the antral part of the stomach, and therefore G-17 levels are expected to be
decreased in antral atrophy [21–23]. However, the concentrations of G-17 in the circulation
are influenced by several factors, and as a result the sensitivity for diagnosing atrophy in theantral part of the stomach is unsatisfactory (15.4% in a fasting state and 30.8% after
stimulation) [24].
4. Non-invasive GastroPanel testing for gastric cancer risk stratification – the Russianstudy
The GastroPanel system (Biohit, Finland) is a set of 4 plasma tests: PgI, PgII, G-17, andimmunoglobulin G (IgG) group antibodies to H. pylori infection. Decreased pepsinogen levels
have been found to correlate with increased risk of gastric cancer in Japan; however, suchdata were not previously available in a Caucasian population. A study in a population-based
cohort of 9360 individuals recruited within the Health, Alcohol and Psychosocial factors inEastern Europe (HAPIEE) study, aged 45–69 years at the time of recruitment, has beenreported from Novosibirsk, a city in Russian Siberia. Within a follow-up period of 6 years, 25
gastric cancer cases were identified and included in the initial report. Every gastric cancer
case was matched to two controls. In patients with decreased pepsinogen levels (PgI/II < 3),
the odds ratio (OR) for developing gastric cancer was 4.31 (95% confidence interval, 1.49–
12.45); however, decreased G-17 levels did not reach statistical significance to reveal gastriccancer risk. With respect to H. pylori positivity, statistical significance was not reached either,although seropositivity was high in both groups (80% in the cancer group and 69.4% in thecontrol group) [25].
During the subsequent analysis several years later (follow-up period, 8 years), which has
been reported in an abstract format so far, more cancer cases were revealed in the study
group. A total of 60 gastric cancer cases and 120 controls were included in the case–control
design. The odds ratio of PgI/II < 3 reached statistical significance as a risk factor for gastriccancer (odds ratio, 3.0; 95% confidence interval, 1.4–6.4) [26].

465. Blood-sample-based gastric atrophy prevalence studies
Three different types of prevalence studies have been reported. The most informative typeare studies conducted in a representative population-based sample that is randomly
selected and of sufficient size. The second type are studies conducted in generally healthy
populations that are invited to participate in the intervention; some preselection bias cannot
be excluded with this design. The third type are studies conducted either in a hospital-based
population sample or in referrals for certain interventions, for example upper endoscopy.
These three types of study are discussed here.
5.1 Population-based studies with random selection
The largest population-based cohort study (ESTHER) recruited a total of 9953 participants(45% male) aged 50–74 years in Saarland in south-western Germany between 2000 and
2002. PgI and PgII were detected in serum by the ELISA method (Biohit). With the cut-off
values for atrophy PgI < 70 ng⁄mL and PgI/II < 3, the prevalence of atrophy in this cohort was
5.7% [27]. Recently, an additional analysis has been performed on the study population,suggesting the rationale of including anti-parietal cell antibody detection to the list of
biomarkers [28].
The Kalixanda study, in Sweden, was a general-population based study (mean age,
54.0 years; 51.2% women; participation rate, 73% of the eligible population). Serum samples
from 978 individuals were included in the analyses for pepsinogens and G-17 (GastroPanel);importantly, endoscopy with appropriate biopsy workup was performed in nearly all thecases. The cut-off value for pepsinogen tests to detect atrophy was PgI < 25 µg⁄L and/or
PgI/II < 3. Based on the serum test results, multifocal (antrum and corpus) atrophic gastritis
was revealed in 1.1% of people and corpus-limited atrophic gastritis in 5.4%; therefore,
blood tests for atrophy revealed a 6.6% overall prevalence [29].
A different testing modality was used in a large population-based study in Latvia. Plasma
samples from a total of 3564 individuals were available (median age, 54 years; 34% male).
PgI and PgII were detected in plasma by the latex agglutination method (Eiken ChemicalCo., Japan), and two different cut-off values were used: PgI ≤ 70 ng/mL and PgI/II ≤ 3 for
atrophy of any grade; PgI ≤ 30 ng/mL and PgI/II ≤ 2 for advanced atrophy. With thesecriteria, the overall prevalence of atrophy was found to be 40.5%, whereas that of advanced
atrophy was 13.3% [11].
Another population-based sample predominantly in a Caucasian population is available from
Krasnoyarsk, a city in eastern Siberia (principal investigator, V. Tsukanov). A total of 801
subjects were involved (48.3% male; participation rate, 94.2% of the invited population). The
Biohit ELISA test system was used to measure pepsinogen levels in serum, with cut-off
values of PgI < 25 µg⁄L and PgI/II < 3. In this population with highly prevalent H. pylori
infection (seroprevalence, 90%), the pepsinogen levels indicated the presence of atrophy in
10.9% of participants [30]. Recently, the same group reported the seroprevalence of atrophy
in two Mongoloid populations in Siberia with high prevalence of H. pylori infection (about94%) and high, but differing, incidence of gastric cancer; serological signs of atrophy wererevealed in 5.3% of Evenks (total sample size, 527) and 9.4% of Tyvins (total sample size,466) [31].
Using the same approach, a group from Novosibirsk has studied the prevalence of
biomarkers characterizing atrophy in other regions of Russian Siberia (principal investigator,
S.A. Kurilovich). The GastroPanel test system was used; a cut-off value of PgI < 25 µg/L
was considered for corpus atrophy and fasting G-17 < 2 pmol/L for antral atrophy ([32] and
S.A. Kurilovich, personal communication).

47

The prevalence of atrophy as detected with biomarker methods in several population
samples from Russian Siberia is summarized in Table 1.5.1. The evidence from older
studies, some of them based on population-selected individuals, was reviewed by Weck andBrenner in 2006 [33].
Table 1.5.1. Prevalence of atrophy as detected with biomarker methods in several population
samples from Russian Siberia
Test resultsGroup description
Group 1

Group 2

Group 3

Group 4

Novosibirsk,
urban,
Caucasians,
45–70 years

Yakutsk,
urban,
Caucasians,
60–90 years

Yakutsk,
urban,
indigenous,
60–90 years

Yakutsk,rural,
indigenous,
45–70 years(n = 254)(n = 81)(n = 72)(n = 90)

Corpus atrophy

9.1%

12.3%

15.3%

26.7%

Antral atrophy

13.6%

37.0%

36.1%

14.4%

H. pylori IgG

86.6%

72.2–74.1%

72.2–74.1%

72.2–74.1%

IgG, immunoglobulin G.

5.2 Studies in invited healthy individuals
A large cohort study in a population from Portugal, a high-risk region for gastric cancer inEurope, demonstrated the feasibility of the pepsinogen testing approach in a European
population [34]. A total of 13 118 individuals were followed up for 5 years; 446 subjects(3.4%) had decreased pepsinogen levels. Of these, 274 underwent upper endoscopy; 6cancer cases were detected, representing one cancer per 2200 tests or one incident caseper 74 positive tests. However, 3 other cancer cases were detected in those with a negative
pepsinogen test result. The Biohit ELISA test system with pepsinogen cut-off levels PgI< 70 ng/ml and PgI/II < 3 for detecting atrophy was used in this study [34].
Studies on large groups of invited individuals (medical professionals and the general
population) have been conducted in Finland (principal investigator, P. Sipponen) by using
the GastroPanel test system. The prevalence of lesions according to this non-invasive
approach has not yet been reported.
5.3 Hospital/outpatient-department-based samples
In Europe, northern Italy has the largest experience in non-invasive testing with GastroPanelbefore referring patients with dyspeptic complains for endoscopy (principal investigator, F. diMario). During 2003–2012, a total of 6000 subjects were investigated in the Padua region;
8% had results characteristic for atrophy, and 34% were H. pylori-infected. In 2011–2013, a
total of 2000 people underwent testing in the Treviso region; atrophy was present in 4% andH. pylori infection in 26% (F. di Mario, personal communication).
A hospital/outpatient-department-based study was conducted in 818 dyspeptic patients of
Caucasian origin aged 25–75 years in Novosibirsk in Russian Siberia. The GastroPanel test
system was used; a cut-off value of PgI < 25 µg/L was considered for corpus atrophy andfasting G-17 < 2 pmol/L for antral atrophy. The results revealed corpus atrophy in 14.5% of
patients and antral atrophy in 24.6% (A. Belkovets, personal communication).
48

In a recently reported hospital-based cohort in Kazakhstan, 835 patients (median age, 46.8;
43.4% male) were investigated with the GastroPanel test system. The seroprevalence of H.
pylori infection was 62.3%. In 14.1% of the patients, the results were consistent with atrophic
gastritis; in 8.6% the characteristic results for isolated antral gastritis were present, and in
5% for isolated corpus gastritis, but in 4 cases (0.4%) results for atrophic gastritis in both theantral and corpus parts of the stomach were present [35].
Currently, a study is in progress in Latvia to compare different pepsinogen tests (two ELISA
tests and a latex agglutination test) in a hospital-based sample as well as to set the best cutoff values in a Caucasian population. The results obtained will be used and will be further
validated in the GISTAR (Gastric cancer prevention study by predicting atrophic gastritis)
study.
6. New biomarker developments
During the past decade there has been a growing interest in other biomarkers for the early
detection of gastric cancer. Multiple studies have evaluated the role of host genetic
polymorphisms to stratify risk of gastric cancer development; although an association ispresent, due to the insufficient strength of the association, these polymorphisms cannot be
used as biomarkers. Extensive work has been conducted to study the potential role ofmicroRNAs (miRNAs) as gastric cancer biomarkers, and several reviews have been
published recently of the miRNAs that are upregulated or downregulated in gastric cancer[36–39]. There is potential that a panel of miRNAs may become a reliable marker for either
detection or prediction of gastric cancer. New proteomic markers have been sought. In
addition, recent studies suggest the potential of proteomic or miRNA marker expression in
extracellular vesicles, including exosomes, microvesicles, retrovirus-like particles, andapoptotic bodies, as a cancer biomarker [40]. To date limited work has been conducted inthis field, specifically with respect to gastric cancer, and the studies are still in progress.
Here, more detailed information is provided about two potential biomarkers, on which studies
have been published recently: cancer autoantibodies and volatile markers.
6.1 Cancer autoantibodies
Autoantibodies against tumour-associated antigens have been identified in several cancer
types [41, 42]. The frequency of antibodies against particular tumour-associated antigens israther low, typically ranging between 1% and 15%; therefore, a test-panel approach is being
used to explore cancer-specific antibodies [43]. Recently such a search for a test panel was
conducted in gastric cancer; a 45-autoantibody signature was found to discriminate gastriccancer from healthy controls with 59% sensitivity and 90% specificity [43]. Further work toincrease the sensitivity of the panel is currently under way.
6.2 Volatile markers
Volatile components found in exhaled breath and identified either by gas chromatography
coupled to mass spectroscopy or by nanosensor technology could become a reliable andeasy-to-use tool for the detection of cancer [44]. A recent pilot study in patients from Chinasuggested that a highly sensitive, cross-reactive, nanomaterial-based gas sensor could be
used to identify and separate volatile marker patterns to distinguish between patients withgastric cancer and those with benign gastric conditions with 89% sensitivity, 90% specificity,and 90% accuracy [45]. However, geographical differences between the content of volatile
substances do exist [46], and therefore local adaptation of the method (“training theelectronic nose”) might be required.

49

Validation studies on gastric cancer-specific autoantibodies as well as volatile markers to be
detected by sensor technologies are currently being designed in Europe (part of this work is
expected to be combined with the GISTAR project).
7. Current European gastric cancer prevention efforts
Current gastric cancer prevention activities in Europe can be divided into (i) scientificprojects and/or pilot projects and (ii) practical implementation activities.
7.1 Scientific field studies and/or pilot studies
A GISTAR study on preventing gastric cancer in a middle-aged population (40–64 years)
was launched in 2013 (pilot study in Latvia) and is reviewed in more detailed separately.
GACSE (Gastric cancer screening in conjunction with colorectal cancer screening in Europe)
is a multicentre study in subjects aged 50 years and older undergoing screeningcolonoscopy (coordinating investigator, P. Malfertheiner; principal investigator, M. Selgrad).
These subjects will be invited to undergo blood sampling for PgI, PgII, G-17, and IgG groupantibodies to H. pylori (GastroPanel). In countries where colonoscopy is not the primarymethod of colorectal cancer screening, blood samples will be taken when colonoscopy isplanned for other clinical indications. Patients with pathological findings in the blood test will
be invited for further investigations. Those with a positive H. pylori antibody test will be
invited for confirmatory non-invasive testing (13C urea breath test or faecal antigen test), andif the presence of the infection is confirmed, they will be offered eradication therapy
consistent with European guidelines. The success of eradication will be investigated with
non-invasive tests. Subjects with decreased pepsinogen levels will be referred for upper
endoscopy with appropriate biopsy sampling, and will be followed up if confirmed to bepositive for atrophy. Recruitment of 4300 subjects is expected to prove the expected 75%
sensitivity of the biomarker test to detect atrophy [47]. Currently a pilot study is in progress in
Magdeburg, Germany. It is planned that the following other countries will join the study: Italy,
Hungary, Serbia, France, Croatia, Poland, Slovenia, and Israel.
A population-based sample in the age range 25–45 years is being recruited in Novosibirsk,
Russian Siberia. A detailed questionnaire is being used, including information on
gastrointestinal disease, and serum and full-blood samples are being collected and stored(the latter for DNA). The target of the recruitment is 3000 subjects; to date, approximately
200 have been enrolled. At present, pepsinogen tests are not scheduled (A. Belkovets,
personal communication).
7.2 Practical implementation activities
7.2.1 Opportunistic GastroPanel screening in dyspeptic patients at the general practice levelin northern Italy
Active promotion of stomach health is under way in northern Italy (principal investigator, F. diMario). Individuals with dyspeptic symptoms at the general practice level are invited toundergo GastroPanel testing, and will be referred to a gastroenterology clinic if found to bepositive for atrophy. The authors consider that the workload for the endoscopy units could bedecreased in this way (F. di Mario, personal communication).
7.2.2 Screening plan for oesophageal and gastric cancers in Kazakhstan
Globally, there are no organized gastric cancer screening programmes functioning outside ofJapan and the Republic of Korea. Kazakhstan, a country close to the European region with ahigh incidence of gastric cancer, has also made the decision to introduce biennial screening
with upper endoscopy for oesophageal and gastric cancers for people in the age group 50–
60 years. Although the national guidelines have not yet been finalized, such a programme
was initiated in 6 of 16 regions of the country at the beginning of 2013, with the intention of50

expanding to the entire country. However, the setup of the programme (lack of quality
assurance in endoscopy and morphology, lack of clear evidence on the management of thelesions revealed) is unlikely to correspond to the criteria of an organized programme;
therefore, the expectations that the target will be reached are low.
In conclusion, although several implementation activities are already under way, more
research data and cost-efficacy estimates are required before any of the currently available
or suggested tests can be recommended in organized cancer screening settings in Europe.
However, the development is in progress, and it is highly likely that an effective screening
test for gastric cancer and/or the related premalignant lesions could be established inEurope.

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Congress, Verona, Italy. Available from: http://www.10igcc.com/download/
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atrophic gastritis: population-based study among 9444 older adults from Germany.
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28. Zhang Y, Weck MN, Schöttker B, Rothenbacher D, Brenner H (2013). Gastric parietal
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31. Tsukanov VV, Vasyutin AV, Amelchugova OS, Tretyakova OV, Saaya A, Rodina DV(2013). Ethnic features of atrophic gastritis prevalence and gastric cancer incidence inthe population of eastern Siberia. [Article in Russian] United European Gastroenterol J.
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Chapter 1.6
Effect of Helicobacter pylori eradication on different subtypes ofgastric cancer: perspective from a Middle Eastern country
Reza Malekzadeh
Gastric cancer is the fifth most common cancer and the third leading cause of cancer-related
death in the world. Close to 1 million new cases of gastric cancer occur annually, and about
750 000 people die from this cancer each year [1]. The incidence of gastric cancer has
declined dramatically during the past 50 years in the USA and western Europe without any
specific preventive measures for gastric cancer (Fig. 1.6.1) [2]. This decline in the incidenceof gastric cancer was also seen in populations in Japan [3] and other high-income countries[3].
Fig. 1.6.1. Age-adjusted cancer death rates in men by site for the USA in 1930–2010 (rates per
100 000, age-adjusted to the 2000 United States standard population). A sharp decline in theincidence of gastric (stomach) cancer is evident without any specific preventive measures for gastriccancer. Source: American Cancer Society (2014) [2].

This remarkable decrease in the incidence of gastric cancer is thought to be due toimprovements in socioeconomic status, along with the almost universal use of refrigeration
as the standard food preservation technique and the availability of sufficient vegetables andfresh fruits and a general improvement in the quality of drinking-water and nutritional statusduring the 20th century [3], with subsequent downward trends in the prevalence ofHelicobacter pylori infection. This large reduction in the incidence of gastric cancer wasachieved before the identification of its major etiological determinants, and during decades
when this neoplasm was neglected in terms of research and prevention efforts [4].
At present, there is a wide variation in the incidence of gastric cancer across the globe. The
Republic of Korea, China, Japan, and Costa Rica are considered high-risk areas, with anage-standardized incidence rate (ASR) per 100 000 person-years of more than 20 in men.

55

Intermediate-risk regions, with an ASR between 10 and 20, include countries like Turkey,
Italy, and the Netherlands, and low-risk regions, with an ASR of less than 10, include India,
Australia, the USA, and Canada [5].
1. Does H. pylori have a protective effect?
In spite of the sharp decline in the overall incidence of gastric cancer across the globe,
several recent reports indicate an increasing incidence of gastric cardia adenocarcinoma,
especially among Caucasians, which parallels an increasing incidence of the
adenocarcinoma of distal oesophagus [6–11]. In the USA, the incidence rate foradenocarcinoma of the gastric cardia among White males is almost equal to the rate for noncardia gastric neoplasm [7].There is now consensus that H. pylori is the most important risk
factor for non-cardia gastric cancer, and there is accumulating evidence that cagA-positive
strains of H. pylori may be inversely related to gastric cardia adenocarcinoma andoesophageal adenocarcinoma [12]. The protective effect of H. pylori has not been proven,but even after excluding the studies with selection or information bias, H. pylori infection isassociated with a reduced risk of Barrett oesophagus [13–16].
If H. pylori could protect against gastric cardia cancer and oesophageal adenocarcinoma,
then the strategy of H. pylori eradication for prevention of gastric cancer could be strongly
questioned, especially in Caucasian populations. Therefore, an exact classification of gastriccancer subtypes is necessary. One major problem is the lack of consensus about theanatomical definition of gastric cardia cancer, which has been defined as tumours thatoriginate 2 cm or 3 cm distal to the gastro-oesophageal junction, and it is quite plausible thatan upward trend observed for incidence of gastric cardia adenocarcinoma is due tomisclassification with distal oesophageal adenocarcinoma. Improvements are needed in thequality of data collected by cancer registries in various countries, and further studies are
required to elucidate time trends in gastric cancer subsites (cardia and non-cardia) globally.
2. Patterns of gastric cancer incidence in the Islamic Republic of Iran
Gastric cancer is the most common cancer in the Islamic Republic of Iran, and the country
includes all three categories of risk areas [17–23]. The southern and northern parts of thecountry are low- and high-risk areas, respectively, whereas the central region is anintermediate-risk area for gastric cancer. This marked variation in gastric cancer incidence
provided an opportunity to study the etiology of gastric cancer in the Islamic Republic of Iran.
The first obvious finding was that differences among the areas in the rate of H. pylori
infection are small, and thus could not explain the large differences in gastric cancer
incidence rates (Table 1.6.1) [24]. It has also been shown that in spite of the almost 2-foldhigher risk of gastric cancer in men, sex differences in the prevalence of H. pylori infection in
the Islamic Republic of Iran are minimal [25].
The high incidence rate of gastric cancer in Ardabil Province, in the north-west of the Islamic
Republic of Iran, was found to be mainly due to higher rates of cardia cancer rather thannon-cardia cancer; the ASR of cardia cancer is 26.4 in men and 8.6 in women [26]. The
same is true for Golestan Province, in the north-east of the country, where up to 50% of
gastric cancers are at the cardia subsite [27].This situation is in contrast to that in other highrisk areas, i.e. Japan and the Republic of Korea and some Latin American countries, where
non-cardia cancers make up the majority of gastric cancers. The fraction of gastric cancers
that are of the non-cardia subtype in low-risk areas of the Islamic Republic of Iran such as
Khuzestan Province, in the south-west of the country, is 85%, which is much higher than thatin Ardabil Province, in the north-west [28]. A recent study by Abdi-Rad et al. showed that the
proportion of proximal gastric cancers in relation to mid and distal gastric cancers isincreasing in Tehran, the capital city [29]. The high incidence of gastric cardia cancer in thenorthern part of the country coincides with a high incidence of squamous cell carcinoma of56

the oesophagus, which may imply some common risk factors for these cancers [30]. Thishypothesis has been supported by studies from other high-incidence areas, in northern
China [31].
Table 1.6.1. Annual incidence of gastric cancer in the Islamic Republic of Iran, reported fromdifferent cancer registries, presented as age-standardized rate (ASR) per 100 000 person-years
Province

Region of thecountry

ASR
Men

Women

Cardia subtype as aproportion of all gastriccancers (%)

Reference

Ardabil

North-western

49.1

25.4

26.2

18

East Azerbaijan

North-western

26.0

11.6

NA

19

Golestan

North-eastern

27.8

8.3

50

20

KermanSouth-eastern

10.2

5.1

NA

21

TehranCentral

19.8

10.0

NA

22

26.1

11.1

NA

23

Islamic Republic of Iran (estimate)NA, not applicable.
Source: Malekzadeh et al. (2009) [24].

3. Risk factors for gastric cancer
Gastric cancer is thought to be the result of continuous cell damage caused by lifelong
exposure to different carcinogens. The intestinal histological subtype of gastricadenocarcinoma, the most common form of gastric cancer, develops in an inflammatory
background induced by H. pylori-related chronic gastritis and progresses to atrophic gastritis,
intestinal metaplasia, glandular dysplasia, and eventually adenocarcinoma [32, 33]. Several
case–control studies and one cohort study in the Islamic Republic of Iran [34–37] haveshown that in addition to H. pylori infection, environmental risk factors including tobacco use,
opium use, high salt intake, and a diet with an insufficient level of antioxidants are involved in
the pathogenesis of gastric cancer. Endogenous and host factors, including those related tomale sex [38], and several genetic backgrounds are known risk factors, to a lesser extent[39, 40]. In addition to the well-established risk factors for gastric cancer, which are mainly
applicable to classic non-cardia cancer, gastro-oesophageal reflux disease (GORD) andobesity have been shown to be two of the main risk factors for cardia cancer [41]. The
association of these tumours with both the H. pylori-related pathway and GORD indicatesthat two distinct types of tumours arise from the anatomical cardia region [41].
4. H. pylori infection
The H. pylori infection rate is very high in the Iranian population (Table 1.6.2) [24]. In a
population-based study in Ardabil Province in 2001–2002, more than 89% of adults aged
40 years or older were found to be infected [42, 43]. In Babol, on the coast of the CaspianSea, H. pylori infection was reported in 78% of men and 82% of women, as determined by
the urea breath test [44]. A population-based study on pastoral nomads revealed that 86%
had H. pylori infection, diagnosed serologically [45]. In a large cross-sectional study in
Tehran, the overall infection rate was 69%, which correlated positively with age, i.e. thehighest prevalence was 79% in the age group 46–55 years [25]. Furthermore, the age atacquisition of H. pylori infection seems to be very low in the Islamic Republic of Iran. Basedon a study in Shiraz, a southern region, 82% of children aged 9 months and 98% of children

57

aged 2 years were H. pylori-infected [46]. A higher prevalence of infection in children andadults and its correlation with age has also been reported in Rafsanjan, another southern
region of the country [47].
Several virulence determinants of H. pylori have been recognized and linked to different
outcomes of infection. The high-molecular-weight protein cagA encoded by cytotoxinassociated gene A (cagA) is present in 60–70% of H. pylori strains and has been shown tobe related to a greater risk of gastric cancer in some populations [48]. In the Islamic Republicof Iran, the majority of H. pylori-infected people have cagA-positive strains. The prevalence
ranges from 66% to 91% at different ages and in different geographical regions [48–50].
Despite the high prevalence of cagA-positive H. pylori in the Iranian population, its
contribution to an excess cancer risk is unclear. A study attempting to clarify the role of cagAin the higher risk of gastric cancer in the Islamic Republic of Iran compared with its
neighbouring country Iraq, where gastric cancer risk is low, found similar proportions ofcagA-positive strains in both countries [49]. Another toxicity determinant of H. pylori is thevacA antigenic region [50]. One natural polymorphic type of this antigen, called vacA i-1, hasbeen shown to be associated with increased gastric cancer risk in the Islamic Republic of
Iran [51, 52]. Other antigenic determinants of H. pylori, such as dupA, have been studied in
the Iranian population and have not shown any clear relationship with gastric cancer risk
[53].
Table 1.6.2. Prevalence of Helicobacter pylori infection in population-based studies in the Islamic
Republic of Iran (2001–2005)
Population(region),year studied

Prevalence

Numberofsubjects

Age (years),mean (SD)Assessment
methodReference

Ardabil(north-western),
2001

All: 89%

M: 49453 (10)

Histology/rapid
urease test

42, 43

Rafsanjan(southern),
2004

M: 72%

M: 11448 (16)

Serology

48

F: 62%

F: 86

Shiraz(southern),
2004

M: 81%

M: 30847

F: 83%

F: 284

Stool antigen
test

Tehran(central),2005

All: 69%

M: 968Serology

25

F: 5178 months to 15 years

36 (14)

F: 1358

F, female; M, male; SD, standard deviation.
Source: Malekzadeh et al. (2009) [24].

5. Atrophic gastritis
Atrophic gastritis is a well-established precancerous lesion for gastric cancer [42]. As
atrophic gastritis is an intermediate step in the carcinogenesis cascade of most intestinaltype tumours and some adenocarcinomas of the diffuse type, its prevalence in the
population strongly correlates with the incidence of cancer. The prevalence of atrophic
gastritis in high-incidence areas of gastric cancer in the Islamic Republic of Iran has beenreported by few studies. In a population-based study of more than 1000 randomly selected,
apparently healthy people in Ardabil Province, atrophic gastritis detected by histology was58

found in 45%, 47%, and 22% of gastric antral, body, and cardiac biopsies, respectively [42,43]. Later, in a case–control study in the same region, a strong association was shown
between atrophic gastritis, defined by the lowest and second lowest quintiles of pepsinogen
I/II ratios (PgI/II), and non-cardia gastric cancer, in multivariate analysis including GORD
symptoms, smoking, and H. pylori serostatus, with odds ratio (95% confidence interval) of
21.47 (2.90–158.76) and 9.08 (1.1–75.29) for the lowest and second lowest PgI/II quintiles,
respectively. A relationship was also noted in multivariate analysis between the lowest
quintile of PgI/II (< 2.37) and a subgroup of gastric cardia cancer (odds ratio, 3.92; 95%
confidence interval, 1.77–8.67) [41]. A high prevalence of serological atrophic gastritis has
also been reported from Babol, in the northern part of the Islamic Republic of Iran: 51% and
53% in studied men and women, respectively – significantly higher than the values in Japan[44].
6. Prevention of gastric cancer
More than 85% of Iranian patients with gastric cancer are being diagnosed at advanced
stages of the disease, and they may gain a borderline survival benefit from conventional
surgical, chemotherapy, or radiotherapy methods [54]. Since the great majority of Iranianpatients with gastric cancer have a current infection or a past history of H. pylori infection(94% and 83% for non-cardia and cardia cancers, respectively) [41], H. pylori infection isconsidered to be a necessary but not sufficient risk factor for non-cardia gastricadenocarcinoma [41]. Other well-established risk factors, including high salt intake, dietaryfactors, and tobacco and opium use, may promote gastric cancer development in an
inflammatory background induced by H. pylori infection. Therefore, any preventive strategies
against H. pylori infection would be a most reasonable action to reduce gastric cancer
incidence. Theoretically, active immunization of young children against H. pylori would be
ideal to prevent infection and its chronic consequences, including peptic ulcer disease andgastric cancer, but currently there is no commercial vaccine for clinical use.
If eradication of H. pylori could be done effectively, and at an early age, the chances forprevention of non-cardia gastric cancer would be much higher.
Eradication of current H. pylori infections in children and young adults may be the best
option for gastric cancer prevention. This can be done in the earlier stages of infection,
before the development of severe atrophic gastritis and intestinal metaplasia. Massive public
eradication of H. pylori in adult populations with high infection rates and prevalent GORD
and a predominance of gastric cardia cancer (i.e. the Islamic Republic of Iran) is impracticalfor several reasons, including the high costs of diagnostic tests and therapy on a national
scale and the danger of development of multidrug-resistant microorganisms.

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63

Chapter 2.1
Effectiveness of Helicobacter pylori eradication
E. Robert Greenberg and Jin Young Park
Although incidence and mortality rates for gastric cancer have been declining in much of theworld, it is still the third leading cause of cancer death globally (behind cancers of the lungand liver) [1] and is a major health problem in many countries of East Asia and Latin America[2]. Chronic infection with Helicobacter pylori causes gastric cancer as well as peptic ulcer
disease, and together these two conditions cause an estimated 1 million deaths annuallyworldwide, with most of the burden borne by populations in low- and middle-income
countries [1, 3]. Current guidelines from different regions differ as to whether asymptomatic
adults should be screened and treated for H. pylori [4], and no countries have implemented
H. pylori eradication programmes as a public health measure. Some of this inaction may
reflect doubts about the effectiveness of H. pylori eradication in preventing gastric cancer,
but there is also uncertainty about possible negative effects of mass antibiotic treatment andabout the feasibility and economic costs of different eradication strategies [5].
This chapter addresses evidence relating to the effectiveness of H. pylori eradication in
gastric cancer prevention; issues of possible negative effects, feasibility, and the cost–effectiveness of eradication programmes are the topics of subsequent chapters. Here,attention is focused on two topics: the importance of H. pylori infection in causing gastriccancer, and recent findings from randomized controlled trials of H. pylori eradication therapy
for preventing gastric neoplasia.
1. H. pylori as a cause of gastric cancer
H. pylori infection is found throughout the world, and the prevalence of infection in adults
varies from 20–50% in higher-income countries to more than 80% in many lower- andmiddle-income countries [6]. The infection is strongly associated with socioeconomic
conditions, and transmission appears to occur through close personal contact, particularly
within the family and typically in early childhood. Once established, infection usually persists
throughout life unless treated. The prevalence of H. pylori infection has decreased in recent
decades, particularly among children in developed countries, probably reflecting
improvements in hygiene [7, 8].
The International Agency for Research on Cancer (IARC) classified H. pylori as a Group 1
carcinogen in 1994 based on a thorough review of relevant laboratory and epidemiologicalstudies [9], and IARC reconfirmed this classification in 2009 [10]. Based on an aggregate
review of the epidemiological literature, an estimated 75% of non-cardia gastricadenocarcinoma cases worldwide can be attributed to H. pylori infection [3]. However, H.
pylori infection often clears spontaneously in chronically infected individuals when they
develop gastric atrophy, a late stage in the carcinogenic process [11], and the enzyme-linked
immunosorbent assay (ELISA) used in earlier epidemiological studies would classify somesuch participants as H. pylori-negative, even though they had been infected for most of theirlives. A more recent large cohort study using a more sensitive anti-CagA immunoblot assay
resulted in a risk estimate associated with H. pylori positivity (odds ratio [OR], 21.4; 95%
confidence interval [CI], 7.1–64.4) that was 3-fold higher than that obtained with ELISA [12],and an analysis based on results of studies using immunoblot serology indicates that H.
pylori infection accounts for 89% of all non-cardia gastric cancers [13]. In higher-riskcountries such as the Islamic Republic of Iran and China, H. pylori infection is also strongly
associated with cancers of the gastric cardia (see Chapters 1.6 and 4.1). Other identified risk

64

factors, such as tobacco use and high salt intake, appear to act primarily in conjunction with
H. pylori.
2. Effectiveness of H. pylori eradication
Recognition of the causal role of chronic H. pylori infection in gastric cancer led someauthors by 2005 to call for broad-scale programmes to eradicate the infection as a way toprevent the disease [14]. However, the proposal met with little support, perhaps because at
the time there were scant data from randomized clinical trials on the effectiveness of thisapproach. Specifically, in 2005 results were available from just three randomized trials thattogether involved only 37 cases of gastric cancer [5] (Table 2.1.1), too few to provide an
informative assessment of the effects of eradication on cancer occurrence. More recently,
however, reports of two randomized trials have been published, in 2008 and 2012, which
included 33 and 86 gastric cancer cases, respectively. Both trials showed a statisticallysignificant reduction in risk among participants randomized to H. pylori eradication therapy[15, 16].
In 2008, the Japan Gast Study Group investigators reported the results of an open-label,randomized trial in which 544 H. pylori-infected patients who had undergone, or were about
to undergo, endoscopic resection for early gastric cancer were randomized to H. pylori
eradication therapy with amoxicillin, clarithromycin, and lansoprazole, or to standard care
(control) [15]. The primary study end-point was new gastric cancer detected on follow-up at asite in the stomach other than that of the original resection. Biopsies of the stomach corpus
at study entry showed moderate or severe atrophy in 75% of participants and intestinal
metaplasia in 49%. On follow-up endoscopy, 75% of participants randomized to eradication
therapy were H. pylori-negative, compared with 5% of those assigned to standard care. After3 years of scheduled endoscopic follow-up, 9 new cancers were diagnosed in the groupassigned to eradication therapy and 24 in the control group (OR, 0.35; 95% CI, 0.16–0.78,
P = 0.003) [15].
The Japan Gast Study Group finding that H. pylori eradication was effective in reducing
gastric cancer risk among patients with previous cancer and a high prevalence of gastricatrophy and intestinal metaplasia indicated that eradication need not occur early in thecourse of carcinogenesis to be effective, as had been suggested in a report from an earlier
trial [18]. An editorial comment that accompanied the Japan Gast Study Group report
recommended implementing large screening and eradication programmes in populations
living in high-risk areas [23]. Other commentators stressed the clinical value of treating
patients after gastric cancer resection, but they also raised concerns about thegeneralizability of the study results to patients without a history of cancer. A subsequent trial
reported from the Republic of Korea used a similar design and noted about 40% fewer newcancers among patients randomized to antibiotic treatment compared with controls (10 vs17), although the result was not statistically significant (P = 0.15) [24], and the authors
concluded that the therapy was therefore ineffective.

65

Table 2.1.1. Published completed randomized trials and their follow-up studies that investigated the efficacy of Helicobacter pylori eradication on gastriccancer incidence
Completed trials of H. pylori treatment and subsequent gastric cancer
Study details andregistration number

Participants
Characteristics

Follow-up
Number

Gastric cancer outcomes
Trial
arm
(n)

Placeboarm(n)Effect estimatea(95% CI)

Previous cancer patients
Fukase et al. (2008) [15],Japan Gast study, Japan(UMIN000001169)

Men and women aged 20–
79 years with early gastriccancer resected

272 H. pylori
treatment, 272
standard care

3 years with gastroscopy

924

OR = 0.35(0.16–0.78)

Choi et al. (2014) [17],Republic of Korea(NCT01510730)

Men and women aged 20–
75 years with early gastriccancer resected

439 H. pylori
treatment, 441
control

2.6–93.3 months(median, 38 months) withgastroscopy

10

17

Not reported(P = 0.15 by logrank)

General population
Wong et al. (2004) [18],China

Men and women aged 35–65

817 H. pylori
treatment, 813
placebo

7.5 years

711

HR = 0.63(0.24–1.62)

Leung et al. (2004) [19],China

Men and women aged 16–
75 years

295 H. pylori
treatment, 813
placebo

5 years

4

6

OR = 0.66(0.19–2.31)

CI, confidence interval; HR, hazard ratio; OR, odds ratio; RR, relative risk.
aA report of further follow-up of the trial referenced above.

66

Table 2.1.1. Published completed randomized trials and their follow-up studies that investigated the efficacy of Helicobacter pylori eradication on gastriccancer incidence (continued)
Completed trials of H. pylori treatment and subsequent gastric cancer
Study details andregistration number

Participants
Characteristics

Follow-up

Number

Gastric cancer outcomes
Trial
arm
(n)

Placeboarm(n)Effect estimatea(95% CI)

Colombian chemoprevention trial
Correa et al. (2000) [20],Colombia

Men and women aged 29–
69 years

491 H. pylori treatment,
485 placebo

6 years3

2

RR = 1.48(0.25–8.83)

Mera et al. (2005) [21],aColombia

Men and women aged 29–
69 years

394 H. pylori treatment,
401 placebo

12 years

5

4

Not reported

Shandong Trial (NCI-OH-95-C-N029)
You et al. (2006) [22],China

Men and women aged 35–
64 years1130 H. pylori treatment,
1128 placebo

7.3 years

19

27

HR = 0.64(0.35–1.15)

Ma et al. (2012) [16],aChina

Men and women aged 35–
64 years1130 H. pylori treatment,
1128 placebo

14.7 years

34

52

OR = 0.61(0.38–0.96)

CI, confidence interval; HR, hazard ratio; OR, odds ratio; RR, relative risk.
aA report of further follow-up of the trial referenced above.

67

In 2012, Ma and colleagues reported the long-term follow-up results of the Shandong
Intervention Trial, a masked, randomized trial in which 2258 H. pylori-seropositive adults
drawn from a general population in China were randomly assigned in a 2 × 2 × 2 factorial
design to three interventions (2 weeks of H. pylori eradication therapy with amoxicillin plus
omeprazole, garlic supplements for 7.3 years, supplemental vitamins for 7.3 years) or theircontrols [16]. Gastroscopies with stomach biopsies were scheduled to occur at study entry
and at follow-up times of approximately 5 years and 9 years after randomization. The
investigators had previously reported the results of the 9-year gastroscopy results, whichindicated that antibiotic eradication therapy significantly reduced the prevalence of
precancerous gastric lesions (OR, 0.60; 95% CI, 0.47–0.75) [22]. At that time there were 19
gastric cancers detected in participants assigned to eradication therapy and 27 in those
assigned to control (P = 0.14). After the 9-year gastroscopy, participants remained underactive clinical follow-up without protocol-specified endoscopy, and by 15 years after
randomization there were a total of 34 gastric cancers in the participants assigned to H.
pylori eradication and 52 in those assigned to the corresponding control (OR, 0.61, 95% CI,
0.38–0.96) [16].
A recent meta-analysis of all six published randomized trials of H. pylori treatment among
asymptomatic infected individuals has yielded an estimated effectiveness of 34% (95% CI,
5–54%) in preventing new gastric cancer [25]. The Shandong Intervention Trial has provided
much of this evidence supporting the strategy of testing and treating for H. pylori, but threeissues complicate interpretation of the estimate of treatment effect size (a risk reduction of
about 40%) reported from the trial.
First, the trial relied on a positive H. pylori serology (ELISA) to determine eligibility for
randomization. Urea breath tests (UBTs) performed within 1 year after randomization
indicated that 12.7–14.6% of participants assigned to the untreated control group wereactually not currently infected with H. pylori. It is reasonable to assume that theseparticipants, and a similar proportion of those assigned to eradication therapy, were notinfected when they were randomized, despite being positive by ELISA testing.
Second, the eradication therapy regimen of amoxicillin and omeprazole was only moderately
effective. Among participants in the eradication therapy arm, only 64% were UBT-negative
after initial therapy [26]. The investigators offered retreatment with the same 2-week regimen
to those who were UBT-positive after treatment, and upon retesting, 74% of the eradicationgroup were UBT-negative. Even these figures provide an inflated estimate of the success ofthe eradication regimen, since they do not take into account the estimated 13% of theparticipants who were uninfected before receiving the study eradication therapy.
Third, there was a high risk of recurrent H. pylori infection after eradication therapy. UBTnegativity in the treated group declined from 74% after completion of therapy to 47% by theyear 7, midway through the entire period of follow-up. This represents an annual risk ofrecurrence of about 7%, assuming that risk was constant over the 7 years.
The net effect of these three aspects of the trial would be a dilution of the “ideal” effect oferadication therapy, i.e. the effect that would be observed if eradication therapy resulted incomplete and sustained absence of H. pylori infection, and if everyone in the control groupremained H. pylori-infected. In fact, there was contamination of both groups, in that about
13% of controls were not infected with H. pylori, and between 26% and 53% of theeradication group were not free of H. pylori infection during the first half of their follow-up
period (presumably, more infections recurred during later follow-up). An estimate was madeof how much the measured effectiveness of the intervention in this trial differed from theeffectiveness that would be observed if the eradication regimen had been 100% successful
and fully sustained, and if all of the controls had been H. pylori-negative. First, it was

68assumed that the control group was contaminated due to inclusion of the 13% who were
uninfected, and that the treated group was contaminated by inclusion of 40% who wereactively infected (the midpoint between the UBT positivity at 1 year and 7 years). Applying
these assumptions, the observed risk reduction of about 40% would translate into an “ideal”
risk reduction of about 75%. This number is comparable to the observed 65% risk reductionin the Japan Gast Study Group trial, in which there was considerably less contamination of
the two study groups. Of course, the estimate of an “ideal” protective effect rests on many
assumptions that cannot be readily verified and are somewhat unrealistic (e.g. 100%
success in eradication, no recurrence of infection), but it provides some perspective on thepossible outcome of a programme that would use a much more effective eradication regimen
than that used in the Shandong Intervention Trial.
3. Conclusions
In summary, given the strong causal link between H. pylori and non-cardia gastric cancer,
the 3–4 billion people who are already infected with the organism represent a vast reservoirof potential cancer cases that will emerge in coming decades unless effective preventive
measures are implemented. When viewed in the context of the epidemiological andlaboratory evidence for the carcinogenic activity of chronic H. pylori infection, the recently
reported results from randomized trials appear to provide compelling support for a large
preventive effect of H. pylori eradication in gastric cancer. Nevertheless, important questionsof programme costs, feasibility, appropriate target groups for intervention, and the potential
harm of mass therapy with antibiotics must first be resolved before implementing large-scale
programmes. The answers to these questions will likely require region-specific data andcost–benefit analyses. Important data are likely to emerge from randomized trials that are
currently in progress or about to begin [5], and additional information could be obtained byinitiating pilot programmes of H. pylori eradication in areas where gastric cancer risk is
especially high.

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Long term follow up of patients treated for Helicobacter pylori infection. Gut. 54(11):1536–40.
http://dx.doi.org/10.1136/gut.2005.072009 PMID:15985559
22. You WC, Brown LM, Zhang L, Li JY, Jin ML, Chang YS, et al. (2006). Randomized
double-blind factorial trial of three treatments to reduce the prevalence of precancerous
gastric lesions. J Natl Cancer Inst. 98(14):974–83. http://dx.doi.org/10.1093/jnci/djj264
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23. Talley NJ (2008). Is it time to screen and treat H pylori to prevent gastric cancer? Lancet.
372(9636):350–2. http://dx.doi.org/10.1016/S0140-6736(08)61136-8 PMID:18675670

7024. Cho SJ, Choi IJ, Kook MC, Yoon H, Park S, Kim CG, et al. (2013). Randomised clinical
trial: the effects of Helicobacter pylori eradication on glandular atrophy and intestinal
metaplasia after subtotal gastrectomy for gastric cancer. Aliment Pharmacol Ther.
38(5):477–89. http://dx.doi.org/10.1111/apt.12402 PMID:23822578
25. Ford ACF, Forman D, Hunt RH, Yuan Y, Moayyedi P (2014). Helicobacter pylori
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26. Gail MH, Pfeiffer RM, Brown LM, Zhang L, Ma JL, Pan KF, et al. (2007). Garlic, vitamin,
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PMID:17760729

71

Chapter 2.2
Are there benefits of Helicobacter pylori infection?
Julie Parsonnet
The popular press has become captivated by the possibility that Helicobacter pylori – anestablished cause of ulcers and cancer – may actually provide some benefits to humans [1–4]. For example, articles in The Economist, The New Yorker, Scientific American, and The
New York Times Magazine highlight the unintentional extinction of elements of the
microbiome and the idea that H. pylori should be preserved. The argument has been madethat H. pylori, a ubiquitous colonizer of human stomachs for many millennia, must provide
some survival advantage. Certainly, other “normal flora” coexisting in humans are
considered beneficial. Following on this teleological argument, since the prevalence of H.
pylori has been decreasing rapidly over the past century, one might infer that its hostbenefits have also been decreasing. Either the diseases it putatively prevents are no longer
a threat or the benefits that H. pylori imparts have been usurped by other organisms or
exposures. In this chapter, the putative benefits of H. pylori are summarized, by dividingthem into two categories: (i) immunological benefits and (ii) physiological benefits.
1. Potential immunological benefits of H. pylori
H. pylori is a potent stimulator of the innate and adaptive immune responses, both within thestomach and systemically. The gastric epithelium releases cytokines that attract and activate
neutrophils and macrophages within the gastric epithelium [5, 6]. A variety of H. pylorispecific T cells can be found within the mucosa, including memory CD4+ αβ T cells and a
predominance of T helper 1 (Th1) and Th17 cells, and few Th2 cells. Despite the tendency
towards a cellular response, individuals with H. pylori also have a strong humoral responsewith high levels of circulating antibodies – particularly immunoglobulin G (IgG), but also IgA.
As infection becomes chronic, dendritic cells induce regulatory T cell (Treg) activity, resulting
in downregulation of the Th1 and Th17 responses, contributing to persistence of infection [6].
This downregulation benefits both the host, by minimizing gastric damage, and theorganism, by decreasing bacterium-specific killing (Fig. 2.2.1) [7].
1.1 Diseases of immune regulation
Because H. pylori has been decreasing in prevalence in the USA and western Europe at thesame time as the prevalence of allergic diseases has been on the rise, some havespeculated that H. pylori infection prevents immunologically mediated diseases. The firstwork on this topic dates from 2002, when Kosunen and colleagues noted an inverse
relationship between IgE directed against inhalant antigens and H. pylori seropositivity [8].
Although others had previously reported inverse correlations between allergy and entericpathogens, this study was the first to identify a specific H. pylori link. Subsequently, in 2007,
Chen and Blaser reported that children with both asthma and allergic rhinitis in the Third
National Health and Nutrition Examination Survey (NHANES III), a large, cross-sectional
population-based study in the USA, were less likely than other children to have H. pylori
antibodies [9]. Multiple studies – including cross-sectional, case–control, and cohort studies– followed thereafter, and three meta-analyses have concatenated the results (Table 2.2.1).
The accumulated data indicate a negative association between H. pylori and allergy,
although the results are inconsistent and even conflicting. The cohort studies – typically themost informative of studies – yielded the least convincing results: one study showed an
association between H. pylori and wheezing but not other forms of atopy [10], a second
showed an association with eczema but not wheezing [11], and a third showed less skin test
reactivity in children with H. pylori but no association between H. pylori and symptoms [12].

72The largest cross-sectional studies demonstrated consistent protection of H. pylori in asthma[13]. None of these studies, however, controlled for the many infectious and socioeconomic
confounders that H. pylori infection – an organism closely linked to both socioeconomic
status and poor childhood hygiene – may portend.
Fig. 2.2.1. Immunological link between Helicobacter pylori and asthma. DC, dendritic cell; IgE,
immunoglobulin E; MLN, mesenteric lymph nodes; TLN, tracheal lymph nodes; Treg, regulatory T cell.
Source: Arnold et al. (2012) [7]. Copyright © 2012 Arnold, Hitzler, and Müller.

The strongest linkages between H. pylori and allergies, and more specifically asthma, derivefrom physiological studies. In both animals and humans, Treg activity related to H. pylori
infection can mitigate atopy, and particularly asthma. For example, in a mouse model, H.
pylori infection skewed the immune response towards tolerance, protecting the mice against
airway hyper-responsiveness, tissue inflammation, and goblet cell metaplasia, andpreventing tissue infiltration with eosinophils, Th2 cells, and Th17 cells [7, 25]; these effects
were mediated by Tregs. Moreover, dendritic cells exposed to H. pylori in vivo and in vitro
enhanced Treg differentiation, indicating that H. pylori-reactive dendritic cells drive thistolerance. In 2013, Oertli and colleagues demonstrated that the tolerizing activity of dendritic
cells can be induced with two H. pylori-associated proteins: γ-glutamyl transpeptidase andvacuolating cytotoxin [26]. Thus, a picture is beginning to hold together in which H. pylori
proteins foster lipopolysaccharide stimulation of dendritic cells that in turn stimulate Tregs,
decreasing gastric inflammation and systemically reducing allergic responses. It should be
noted, however, that mice are not a natural host for H. pylori, and similar physiologicalstudies in humans have not yet been conducted.

73

Table 2.2.1. Meta-analyses on protective effects of Helicobacter pylori on disease
DiseaseNumber ofstudies

Summary OR (95% CI)

Asthma (meta-analysis a)14

Asthma (meta-analysis b)aAsthma (meta-analysis c)
Oesophageal cancer

Oesophageal cancer

Oesophageal cancer

Barrett oesophaguscBarrett oesophagus
GORDa

Publication
year

Reference

0.84 (0.73–0.96)

2013

14

19

0.81 (0.72–0.91)

2013

13

5

b

1.01 (0.82–1.24)

2012

15

16

0.97 (0.76–1.24) (squamous)

2013

16

16

0.59 (0.51–0.68) (adenocarcinoma)9

1.10 (0.78–1.55) (squamous)

2008

17

13

0.56 (0.46–0.68) (adenocarcinoma)

50.80 (0.45–1.43) (squamous)

2008

18

9

0.58 (0.48–0.70) (adenocarcinoma)

49

0.73 (0.60–0.88)

2012

19

9

0.50 (0.27–0.93)

2009

20

19

0.64 (0.49–0.83)

2013

21

d

1.99 (1.23–3.22)

2013

21

d

0.81 (0.56–1.17) symptoms

2011

22

2010

23

2010

24

GORD after H. pylori
eradication

12

GORD after H. pylori
eradication

10

GORD after H. pylori
eradication

6

1.11 (0.81–1.53) (RCTs)

5

1.37 (0.89–2.12) (cohort studies)

Inflammatory bowel
disease23

0.64 (0.54–0.75)

1.13 (0.72–1.78) oesophagitis

CI, confidence interval; GORD, gastro-oesophageal reflux disease; OR, odds ratio; RCTs, randomized controlled trials.
a

All case–control studies.

bOverlap in these meta-analyses: 12 of 14 studies in meta-analysis a are included in meta-analysis b; 4 of 5 studies inmeta-analysis c are included in meta-analysis b.

cFour unbiased studies had OR of 0.46 (95% CI, 0.35–0.63).

d

All RCTs. There are 6 studies included in both analyses.

Invoking similar mechanisms to asthma, investigators have posited associations between H.
pylori and other immune-mediated diseases, including eczema, allergic rhinitis, andinflammatory bowel disease [24]. Whether any of these diseases will truly be linked toabsence of H. pylori remains to be seen.
1.2 Infectious diseases: tuberculosis and gastroenteritis
The putative inverse association between H. pylori and allergic diseases is thought to reflect
downregulation of Th1 and Th17 pathways. However, other studies suggest that H. pylori

74

stimulates vigorous Th1 responses. Such responses have the potential to protect against
infectious diseases. For example, H. pylori, by decreasing gastric acidity, could increase therisk of gastrointestinal infections. In two separate studies, however, the opposite was foundto be true: H. pylori was negatively associated with symptomatic gastrointestinal infection. In
a longitudinal cohort, household members with H. pylori infection were found to be less likely
than uninfected household members to acquire gastroenteritis from a sick family member(odds ratio, 0.25) [27]. Moreover, in an experimental exposure to enteropathogenic
Escherichia coli (EPEC), adults with H. pylori infection had attenuated symptoms of infection[28]. Similarly, pre-existing H. pylori was found to negatively correlate with activation of latenttuberculosis both in monkeys and in humans [29]. It was speculated that the neutrophilactivating protein of H. pylori could promote Th1 cytokines in response to tuberculosis andother antigens [29, 30]. Other investigators have not found similar protective effects of H.
pylori, however. For example, field studies have associated H. pylori with increased risk of
Shigella gastroenteritis and with severe cholera, although in both cases confounding could
not be excluded [31, 32]. Further work on H. pylori immunity is needed to elucidate thebalance between enhanced immunity and immune tolerance.
2. Potential physiological benefits of H. pylori
In addition to immunological effects, H. pylori causes profound changes in the gastricmucosa, including alterations in gastric hormone and acid secretion. Several diseases havebeen linked to the absence of these H. pylori-associated physiological effects.
2.1 Oesophageal diseases
At the same time that H. pylori and ulcer disease have been disappearing from many
populations, the prevalence of gastro-oesophageal reflux disease (GORD), Barrett
oesophagus, and oesophageal adenocarcinoma have been on the rise. These threediseases are thought to represent a continuum of the same process, with reflux leading to
specialized metaplasia in the oesophagus (Barrett oesophagus), which can then ultimately
give rise to oesophageal adenocarcinoma. Thus, risk factors for GORD will necessarily berisk factors for other diseases further down the chain. Risk factors for GORD, including
obesity, cigarette smoking, hiatal hernia, advanced age, diets rich in nitrates, and male sex,
have all, also, been linked to Barrett oesophagus and oesophageal adenocarcinoma [33].
More recently, however, investigators have linked the absence of H. pylori – and more
specifically, the absence of CagA-positive H. pylori – to this pathophysiological pathway fromdamage to metaplasia to malignancy.
In general, two types of human studies inform the observed associations with oesophageal
diseases: treatment trials (both randomized controlled trials and cohort studies) showing
increases in GORD prevalence with H. pylori eradication, and observational studies linking
infection to GORD, Barrett oesophagus, and oesophageal cancers. Results of these studies
have yielded widely disparate results, particularly for GORD. Based in large part on a 2010
meta-analysis of 7 randomized clinical trials and 5 cohort studies, the Maastricht IV
consensus statement concluded that “eradication of H. pylori in populations of infectedpatients, on average, neither causes nor exacerbates GORD” [34]. In contrast, a more
recent meta-analysis assessing 12 randomized clinical trials and 12 cohort studies did findan increased risk of GORD in those treated for H. pylori [21].
Part of the disagreement may arise from the analytic criteria (per protocol vs intention totreat vs eradicated or not eradicated infection), the outcome used (symptoms vsoesophagitis), and the region of the world where the studies were conducted; studies fromthe Far East show the strongest association between lack of infection and GORD. However,a body of physiological data has accumulated over the past 10 years that supports a causal
role for H. pylori in protecting against GORD. H. pylori is known to reduce acid secretion in75

the stomach, over time. Since erosive oesophagitis is a consequence of acid secretion, theabsence of acid should protect against GORD. Eradication of the organism can cause arebound in acid production, which can explain the onset of erosive oesophagitis inpredisposed individuals. Moreover, H. pylori is also linked to obesity (see below), although
the data are far from definitive.
Studies on Barrett oesophagus and oesophageal adenocarcinoma show less variability thanstudies on GORD. Maastricht IV concluded that “there was a negative association between
the prevalence of H. pylori and the severity of GORD and incidence of oesophageal
adenocarcinoma”. This conclusion conforms with many clinical studies as well as metaanalyses listed in Table 2.2.1.
Whereas the negative association between H. pylori and oesophageal adenocarcinoma is
now becoming widely accepted, substantial uncertainty remains as to whether H. pylori also
contributes to squamous cell carcinoma of the oesophagus. Neither the accumulated data
nor physiological studies, however, yet provide coherent support for this association.
2.2 Obesity
H. pylori has long been linked to stunting in young children. When H. pylori eradication was
also linked to GORD, investigators began to posit effects on adult weight and on causing theobesity epidemic. Given the day-to-day and time-to-time variability in weight, as well as thenormal weight gain with increasing age (an estimated 0.5 kg per year), sample sizes
required to conduct the ideal weight study would be quite large. Although the few
randomized controlled trials conducted to date support the H. pylori–weight association, thedifferences are small and often difficult to interpret [35]. Certainly the magnitude of change
observed to date is unlikely to account for the “obesity epidemic”. Moreover, treatment of H.
pylori eliminates a wide variety of colonizing infections; given the suspicion that the gut flora
more generally influence weight, the lack of specificity of antibiotics renders imputing
specificity of the H. pylori effect impossible. Yet, there are plausible physiologicalmechanisms by which H. pylori could influence weight. The most well studied is the rise inlevels of ghrelin – a hormone that plays a role in appetite regulation – in patients after
eradication of H. pylori infection [36, 37]. Other putative effects are alterations in leptin andother adipocytokines, increased appetite due to diminished abdominal pain, and differencesin other aspects of the microbiome due to the presence of H. pylori.
3. Conclusions
Human beings are ecosystems of microorganisms. Is it far-fetched to imagine that changes
in one member of the community, i.e. loss of H. pylori, might cause unpredictable alterationsin the overall well-being of the entire ecosystem? The mere fact that H. pylori is disappearing
from the human host without substantive intervention might indicate that, in many countries,
it is providing little benefit. The large clinical trials of H. pylori eradication currently under way
in China and Europe, if carefully monitored for a wide variety of outcomes, can provide more
substantive insights on how H. pylori specifically and the entire human microbial ecosystemaffect human health.

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79Chapter 2.3
Potential impact of bacterial resistance after population-based
Helicobacter pylori treatment
Francis Mégraud
The discovery of antibiotics was one of the most important breakthroughs of the 20th
century. Life-threatening infectious diseases that had long been the main cause of humanmorbidity and mortality, especially in children, suddenly became curable.
However, there is always the other side of the coin. Very quickly bacteria began to adapt tothese drugs by acquiring resistance mechanisms. Resistance to antibiotics is currently oneof the most important challenges with which medicine is faced. One can now find bacteria
resistant to virtually all existing antibiotics. Public health measures have been taken in many
countries to limit the use of antibiotics or at least to use these drugs in a reasonable manner,
thanks to education of the general population [1] and stewardship programmes in hospitals[2]. Therefore, the implementation of health programmes that lead to a massive use ofantibiotics must be questioned. This chapter briefly reviews the basis of antimicrobial
resistance, the relationship between antibiotic consumption and bacterial resistance, and theimpact of antibiotic consumption on the composition of the microbiota.
1. Basis of antimicrobial resistance
Genetically speaking, antimicrobial resistance can be due either to point mutations or tomobile genetic elements. In resistance due to mobile genetic elements, plasmids,
transposons, and integrons are the most threatening in terms of diffusion. Plasmids replicate
independently of the chromosomes, support resistance mechanisms to several antibiotics,
and can be transferred from bacterium to bacterium, usually between phylogeneticallyrelated bacteria but even sometimes in less-related bacteria. This horizontal transmission
leads to outbreaks in the bacterial population. In contrast, resistance due to point mutation is
only transmitted vertically to the descendants of the bacteria that acquired the mutation.
Mutations arise by chance in a few bacteria in the bacterial population and are then selectedby the antibiotic when it is used.
Antimicrobial resistance due to mobile genetic elements occurs mainly in Gram-negative
bacteria other than Helicobacter pylori, for example Enterobacteriaceae, and affects mainly
antibiotics from the β-lactam and aminoglycoside groups. It occurs more frequently in closed
environments, such as hospitals where antibiotic consumption is very high and where
immunosuppressed patients are present.
Fortunately, with regard to H. pylori, only point mutations and vertical transmission are
involved. Mutations have been found for all antibiotics used to treat H. pylori (Table 2.3.1)[3–9], but they are clinically relevant essentially for macrolides and fluoroquinolones [10].
The question arises as to the stability of these mutations. Indeed, if the mutation has a costfor the bacterium, i.e. an impact on its growth and replication, or its “fitness”, then themutation will not persist from generation to generation and the wild type, without the
mutation, will make up the majority of the population [11]. Another possibility is theoccurrence of compensatory mutations, which occur at other sites on the bacterial genome
and compensate totally or partially for the loss of fitness of the resistant mutants [12]. Given
the steady increase in macrolide resistance among H. pylori, it is most likely that the80

mutations for macrolide resistance do not have a major impact on the fitness of thebacterium [13].
Table 2.3.1. Genes involved in point mutation or other genetic events leading to antibiotic
resistance in Helicobacter pylori
Antibiotic group

Genes involved

References

Macrolides

rrn 23S

3Metronidazole

rdxA, frxA

4

Quinolones

gyrA

5

Rifamycins

rpoB

6

Amoxicillin

pbp-1

7

Tetracycline

rrn 16S

8, 9

Source: Reproduced from Mégraud (2004) [10], with permission from BMJ Publishing Group Ltd.

Mechanistically speaking, point mutations lead to a modification of the antibiotic target, forexample 23S ribosomal DNA for macrolides, which prevents the binding of the drug. In othercases, they cause a modification of the penetration of the drug. A mechanism comprisingproduction of an enzyme to destroy the antibiotic outside of the cell has not been found in H.
pylori. The presence of efflux pumps can, however, also be implicated for tetracycline andmetronidazole.
2. Relationship between antibiotic consumption and bacterial resistance
2.1 At the population level
The relationship between antibiotic use and bacterial resistance has been extensively
studied in the context of hospitals, where horizontal transmission occurs. Resistance occurs
frequently, but it is easy to implement interventions, i.e. to stop the use of the antibiotics in a
relatively controlled environment, and then to have a strong argument of causality. It is moredifficult to tackle the relationship in the community, where many determinants are notcontrolled – for example, the antibiotic residues present in food that are a consequence of
the use of antibiotics in veterinary medicine – and where interventions are rarely performed.
A study was conducted to assess the resistance rates of H. pylori to certain antibiotics(macrolides, fluoroquinolones) and the link with outpatient antibiotic use in 17 European
countries. Data for consumption were expressed as defined daily dose (DDD) per 1000
inhabitants per day, and H. pylori strains were collected in centres across Europe. A goodcorrelation was obtained for fluoroquinolones (Fig. 2.3.1). The correlation was notstatistically significant for macrolides when analysed together but was significant when only
long-acting macrolides were considered [14].

81Fig. 2.3.1. Correlation between quinolone (J01M) use in 2005 and Helicobacter pylori resistance to levofloxacin in 2008–2009. CI, confidence interval; DID,
defined daily dose per 1000 inhabitants per day. Country codes: AT, Austria; BE, Belgium; HR, Croatia; FI, Finland; FR, France; DE, Germany: GR, Greece;
HU, Hungary; IE, Ireland; IT, Italy; NL, The Netherlands; NO, Norway; PL, Poland; PT, Portugal; SI, Slovenia; ES, Spain; UK, England only. Source:
Reproduced from Mégraud et al. (2013) [14], with permission from BMJ Publishing Group Ltd.

n = 18% resistance

Levofloxacin-resistant H. pylori (%)

45%

P = 0.0013

Observed levofloxacin resistance rate
Predicted levofloxacin resistance rate
Lower limit of 95%CI
Upper limit of 95%CI

40%y-Intercept (95%CI): –3.081 (–3.666 to –2.496)
Slope (95%CI): 0.519 (0.228 to 0.811)

35%
30%

BE

HU

25%

PT

 n ≥ 300

20%

DE

IE
FI

10%
UK

5%

NO

 n < 200

ES

AT

NL

 n < 300

IT

FR

15%

GR



HR

SI
PL



0%
0

0,5

1

1,5

2

2,5

3

3,5

Outpatient use of quinolones (J01M) in 2005 (DID)82n < 100n < 50Another major study in this area was carried out in Finland, where Seppälä et al. studied theeffect of macrolide consumption on erythromycin resistance of Streptococcus pyogenes.
After an increase in macrolide resistance of S. pyogenes, the policy on outpatient antibiotic
use was changed throughout the country in the early 1990s, especially concerning
limitations of macrolide use for respiratory and skin infections. After this decision, S.
pyogenes resistance to erythromycin was monitored over 7 years (53 900 isolates). The
researchers observed a decrease in the DDD per 1000 inhabitants per day from 2.40 to
1.38, and the percentage of S. pyogenes macrolide resistance decreased by almost 50%,
but only after a 5-year delay (16.5% in 1992; 8.6% in 1996) (Fig. 2.3.2) [15].
Fig. 2.3.2. (A) Evolution of macrolide consumption by outpatients in Finland (1976–1995).
Consumption is expressed in terms of defined daily doses per 1000 inhabitants per day. (B) Evolutionof Streptococcus pyogenes resistance to erythromycin in Finland (1990 and 1992–1996). Source:
From Seppälä et al. (1997) [15], copyright © 1997 Massachusetts Medical Society. Reprinted withpermission from Massachusetts Medical Society.

A
Erythromycin

Macrolide consumption(doses/1000/day)

Roxithromycin
Azithromycin

P = 0.02

3

Clarithromycin

P = 0.007

2.5

P = 0.01

2
1.5
1

0.5
0

1978

1983

1988

1993 YearB% resistance
30
25

19.0

20
15

13.2

15.6

16.5

10.0

10

8.6

5
0

1990

1991 1992

1993

1994

1995

1996 YearThe results of these two studies, one ecological and the other an interventional study, pointout that a positive relationship exists between antimicrobial use and development ofresistance.

832.2 At the individual level
The impact of the standard clarithromycin-based triple therapy on H. pylori has been well
documented over the years. Indeed, when this treatment fails, approximately 60–70% of thestrains test resistant to clarithromycin [16]; when levofloxacin is used instead ofclarithromycin, about 50% of the strains test resistant to fluoroquinolones when the treatment
fails [17]. An increase in metronidazole resistance is also observed under suchcircumstances.
Besides H. pylori resistance, it is also important to consider the resistance induced by H.
pylori eradication therapy on other bacteria, especially the faecal flora. Currently, very few
studies are available. They were conducted mainly in Sweden and concern essentially theconsequences of the standard clarithromycin-based triple therapy. In a study of the stool,throat, and nostril flora of 85 patients who received clarithromycin, metronidazole, andomeprazole for 1 week, the researchers focused on four bacterial species. A dramaticincrease in resistance was observed 2 weeks after the start of treatment among all strainsthat were previously susceptible: Streptococci (80%), Staphylococci (72%), Enterococci(67%), and Bacteroides (27%). After 1 year, the probability of persistence of resistantorganisms was 51% for Streptococci, 39% for Staphylococci, 14% for Enterococci, and 14%
for Bacteroides [18].
That study confirmed the results previously obtained on throat flora only, where Streptococci
and Neisseria sp. were chosen as indicator organisms and a follow-up was carried out
1 year and 3 years after patients received the same eradication treatment. Resistance wasfound to increase after treatment in all cases except one; after 1 year, resistance was still
higher than at inclusion, but it reverted to baseline levels after 3 years [19].
Another study showed that anti-H. pylori treatment selects for highly resistant Enterococci,
which were able to persist for 3 years in 3 out of 5 patients [20].
These data indicate that anti-H. pylori treatment has an important and long-lasting impact on
resistance of normal bacterial flora.
3. Impact of antibiotic consumption on the composition of the microbiota
The few studies that have been performed on this topic were based on standard culture
methods and not the current metagenomics approach. Two studies were performed in
Sweden in the 1990s. In the first study, 14 patients received omeprazole–amoxicillin (OA) for
10 days and were compared with 14 who received a placebo. In the second study, 14
patients received omeprazole–amoxicillin–metronidazole (OAM) and 16 received
omeprazole–clarithromycin–metronidazole (OCM), both groups for 7 days.
Significant alterations were seen in the saliva microbiota of the patients who received OA.
The number of viridans streptococci increased, and the number of Haemophilus sp.
decreased. The anaerobic microflora was significantly reduced. Levels returned to normal
after 35 days. In the group who received OAM, similar results were observed, with anadditional increase in the numbers of yeasts. The same was true for the OCM group.
Concerning the intestinal microbiota, in the OA group, in addition to the emergence ofresistant enterobacteria, yeasts emerged. With OAM and OCM treatment, there was also asignificant increase in the numbers of Enterococci, Enterobacteria, and Peptostreptococci.
Anaerobic bacteria such as Bifidobacteria and Clostridia were significantly suppressed.
These alterations returned to normal 4 weeks after treatment in the OAM group but persisted
for the OCM group [21].

84Another study, performed in Germany, investigated the impact of OCM on the intestinal
microflora of 57 patients and 21 controls [22]. The researchers also observed a decreasedcolonization with non-spore-forming anaerobic bacteria and an increased colonization withyeasts including Candida albicans, and with Clostridia, after treatment. Clostridium difficile
was detected in 3 cases but without associated diarrhoea.
Although C. difficile enterocolitis has rarely been described after H. pylori eradication
therapy, this is a potential issue to consider in implementing a mass eradication programme.
4. Conclusion
There is evidence of a positive correlation between antibiotic consumption and bacterial
resistance to the corresponding antibiotic, as well as a negative impact on the normal flora,
which is now considered as a specific organ, given its impact in many diseases.
Unfortunately, even the countries with the strictest policy, like the Netherlands, have seen an
increase in antibiotic prescription over the past decade, especially because of the ageing of
the population [23]. A mass H. pylori eradication campaign would no doubt add greatly tothis burden.
However, the precise impact of eradication measures should be calculated in each country,
according to the prevalence of the infection, to see what the real additive effect would be. In
Germany, for example, only an estimated 15% of antibiotics are, in fact, used directly byhumans, whereas 85% are used for veterinary medicine [24].

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5. Moore RA, Beckthold B, Wong S, Kureishi A, Bryan LE (1995). Nucleotide sequence ofthe gyrA gene and characterization of ciprofloxacin-resistant mutants of Helicobacter
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7. Gerrits MM, Schuijffel D, van Zwet AA, Kuipers EJ, Vandenbroucke-Grauls CMJE,
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87

Chapter 3.1
Principles of evidence-based cancer prevention strategies
Karen J. Goodman and Amy Colquhoun
1. What evidence can be used for evidence-based disease prevention strategies?
In the formulation of evidence-based disease prevention strategies, the expected costs andbenefits of proposed strategies must be evaluated against the alternative use of available
resources. In particular, it must be decided whether spending the required resources for aparticular intervention is preferable to using these resources for other priorities. Suchdecisions should be informed by the best available scientific evidence on the expected costs
and benefits of specific strategies, along with prioritization of available resources according
to relevant social values. Expected costs and benefits, as well as available resources andpriorities, vary across population settings; thus, strategies must be tailored to each local
context. This chapter summarizes key principles articulated in authoritative texts onevidence-based disease prevention.
1.1 What is considered “best evidence”?
Evidence for evidence-based practice has been defined as “knowledge derived from avariety of sources that has been subjected to testing and has been found to be credible” [1].
Rycroft-Malone et al. (2004) stated that this knowledge can be gained from a variety ofsources, including: research evidence; professional knowledge or clinical experience;patients, clients, and carers; and local context [2]. Skovgaard et al. (2007) pointed out thatwhat is considered “best, current available knowledge” varies but is sought to [3]: Estimate the need and potential for interventions
 Demonstrate “what works”
 Guide efficient implementation
 Single out action plans that will be more cost-effective than feasible alternatives.
1.2 What types of evidence should be considered?
Brownson et al. (2011) highlighted three levels of evidence to consider in evidence-based
public health [4]: Type 1: whether something should be done, based on analytic data illustrating theimportance of the health condition and its link with some preventable risk factor aswell as the magnitude, severity, and preventability of the condition.
 Type 2: whether a specific action can be identified, based on the relative
effectiveness of specific interventions to address a particular health condition.
 Type 3: how an intervention should be implemented, based on an understanding of
the context of an intervention, including social, cultural, economic, and politicalfactors.
When considering various types of evidence for disease prevention strategies, it may also be
valuable to note differences between evidence used to inform medicine and evidence that is
typically used to inform public health. Brownson et al. (1999) described evidence-based
medicine as “the delivery of optimal individual patient care through the integration of current
best evidence on pathophysiological knowledge, cost effectiveness, and patient preferences”[5]. They noted that much of the evidence used to support medicine is based on randomized
controlled trials. In contrast, they stated that evidence-based public health is “thedevelopment, implementation, and evaluation of effective programs and policies in publichealth through application of principles of scientific reasoning” and noted that public healthinterventions typically rely on evidence from quasi-experimental or observational studies.

88

2. Disease prevention strategies: development and implementation
Teutsch (1992) presented an idealized model for developing and implementing prevention
strategies [6]:1. Basic research produces prevention technologies that may reduce morbidity and/or
mortality.
2. Controlled experimental studies estimate the efficacy of the resulting prevention
technologies.
3. Community-based studies estimate the effectiveness and cost of prevention strategies
based on efficacious prevention technologies, first in demonstration settings and thenin routine community settings.
4. Improvements in methods to increase prevention effectiveness are incorporated
iteratively.
Similarly, Greenwald et al. (1995) listed five phases of cancer control research [7]:1. Hypothesis development
2. Methods development
3. Controlled intervention trials
4. Defined population studies
5. Demonstration and implementation.
Defined population studies should be done after an intervention has been shown to beeffective in a controlled comparison study. Demonstration and implementation should
proceed only after a prevention strategy has passed through the first four phases; there
should be clear scientific evidence from controlled trials demonstrating the extent of benefit,
and information from defined population studies about the practical implementation andcost–effectiveness in a relevant geographical region. Identification of these five researchphases reveals the level of evidence available to support a cancer control intervention, withthe strength of the scientific evidence corresponding to the highest phase achieved. As
noted by Teutsch (1992), pressure to move rapidly from basic and applied research towidespread implementation before the appropriate evaluation studies can be completed
leads to gaps in evidence of the efficacy, effectiveness, safety, or economic impact ofpotential prevention strategies [6]. Generally, however, there should be accurate estimatesof the efficacy and safety of prevention strategies before evaluation in population settings toensure that they have the expected impact [8].
3. Disease prevention strategies: assessing evidence
Skovgaard et al. (2007) presented three types of evidence that together form the evidencebase for disease prevention [3]:Type I. Descriptions and analyses of the determinants of health and disease and theirdistribution.
These help when answering questions like: What do we know about the cause of a given state of health, its distribution, andpossible consequences of preventive interventions to individuals and groups?
 Do we know enough to design actions with the aim of intervening?
 Which target populations should be selected?
 Which interventions might work for the selected target populations?
Type II. Assessments of the relative effectiveness of preventive interventions.
These help when answering questions like: What is the quality of knowledge about the effects of potential preventive
interventions that is available to guide new practice and decision-making?
 What works best on whom?

89Type III. Accounts of the best possible design and implementation of interventions in
specified contextual circumstances.
These help when answering questions like: Is the proposed intervention well suited to the target group?
 What is required for its implementation (organization of services, personnel
qualifications, partnerships)?
 How can user involvement and activity be ensured?
The best evidence for prevention does not consist of studies that establish causality under
optimal conditions. Instead, the need is for real-world investigations of the impact ofprevention strategies under typical conditions. Moving evidence into practice requires
assessing whether effective interventions conducted as research trials can be re-createdunder less-ideal, everyday circumstances. The following questions proposed by Skovgaard
et al. (2007) are useful in guiding such assessments [3]:1. What proportion of the target group would be willing and able to participate in theintervention?
2. Which negative and positive effects can be expected?
3. Will those expected to execute the intervention actually commit themselves?
4. To what degree will the intervention be performed as prescribed?
5. Can the intervention and its effects be maintained over time?
Teutsch (1992) presented a framework for assessing the effectiveness of disease prevention
strategies, including [6]:
 Identification of efficacious and effective strategies to reduce disease and promotehealth.
 Identification of potential consequences of those strategies, including social, legal,
ethical, and economic considerations.
 Estimation of the economic impact of a prevention strategy.
 Identification of optimal methods for implementing effective strategies.
 Evaluation of the impact of prevention programmes.
3.1 Assessing efficacy
As elaborated by Teutsch (1992), evaluating efficacy requires critical review of relevant
studies that have been done, with the goal of assessing the quality of the science and themagnitude of the impact [6]. In health research, the highest-quality study design for efficacy
is considered to be a randomized trial. Many prevention technologies are not subjected tothis level of scrutiny, however, because of the prohibitive costs. Consequently, less-desirable
studies are often used to assess efficacy.
3.2 Assessing effectivenessOnce a prevention strategy is known to be efficacious, the next question is: How well does it
work in the real world? Effectiveness characterizes the success of the prevention strategy intarget populations, allowing for the practical aspects of delivering it to people as part of theirroutine activities. Effectiveness is influenced by problems of access, follow-up, quality
assurance, and individual behaviour in the social context. Effectiveness studies must be
done in the community settings targeted for disease prevention. High-quality assessment of
the effectiveness of prevention strategies comes from community demonstration projects.
The safety of potential prevention strategies must also be evaluated, to identify undesiredconsequences, such as adverse effects, including anxiety created by highlighting potential
health risks. Effectiveness studies can be used to assess the difference between theattributable fraction, interpreted as the proportion of disease cases that would be prevented
by removing an exposure to which they are attributable, and the prevented fraction, which90estimates the proportion of disease cases prevented given the actual implementation of aprevention strategy.
3.3 Economic assessments
Teutsch (1992) also reviewed principles of economic assessments of preventions strategies,
which are needed to evaluate expected costs and benefits of potential prevention strategies[6]. Useful cost–effectiveness analysis fulfils basic criteria:
 Prevention strategies are compared against alternatives, for example doing nothing,using other methods, or addressing different problems.
 The perspective is explicit (e.g. societal, employer, government, insurer), given thatthe perspective determines which costs are included in the analysis and how benefits
are valued.
 Results produce quantified measures that weigh benefits against costs:
o Cost–effectiveness: cost unit per prevented health event, for example dollars
per year of life saved.
o Cost–benefit: cost unit expended per cost unit of benefit achieved.
o Cost–utility: cost unit of utility measures such as number of life-years saved.
 Weighting factors used to adjust cost–utility measures are explicit due to theirsubjective nature (e.g. the length of life a person would be willing to forgo if they
could be freed of the morbidity).
 The method used for discounting is explicit and reasonable in accounting for benefits
that accrue in the future against costs incurred in the present.
Standard methods for economic impacts of prevention strategies are needed to compare
results across studies of these impacts: compared studies must be comparable on
perspective, costs included, how benefits are valued, and methods of adjustment anddiscounting. Many good cost–effectiveness studies of Helicobacter pylori elimination for
gastric cancer prevention have been done, but there is little standardization of methods
across these studies.
4. Disease prevention strategies: who should be targeted, and who should be
involved?
Ockene et al. (2007) described the following levels of intervention [9]: Individual-level interventions: one-to-one interactions between a patient and aprovider, also well suited for including the family in addressing the health needs ofthe individual.
 Social, family, and community network interventions: strategies that target socialgroups in community settings, such as recreation centres, workplaces, schools,
places of worship, and so on; interventions that target the family and social networks
can facilitate behavioural changes at the individual level.
 Community-level interventions: strategies that target communities defined bygeography, race, ethnicity, sex, illness, and so on, with a common interest such as aservice agency, workplace, school, clinic, or policy-makers; such strategies include
broad environmental, regulatory, and policy changes.
Coherent recommendations for evidence-based disease prevention must target explicitly
those expected to implement the preventive practices. It must be clear whether messages
are aimed at public health officials, health-care decision-makers, clinicians, or individuals at
risk. Ockene et al. (2007) called for the integration of evidence-based clinical and community
strategies to improve health [9]. Disease prevention initiatives can be more effective whenbased on coordinated efforts of clinical and community-based interventions to take fulladvantage of opportunities for prevention; thus, targeted health threats should beapproached from a multilevel perspective, through partnerships across health systems,

91communities, academia, business, and the media. Strategies that integrate preventive
services across clinical and public health sectors align with a social–ecological perspectivethat recognizes behaviours and health to be influenced by multiple levels, from the individual
to families to larger groups and, ultimately, to populations and ecosystems. Whenintervention strategies target each level of influence in a complementary manner, support isprovided to those at risk at many different points, such as schools, clinics, and workplaces,
thereby expanding their potential impact.
Example 1. Ockene et al. (2007) characterized the Massachusetts Tobacco Control
Program as a comprehensive coordinated disease prevention programme, which
incorporated clinical and community strategies, linking activities in clinical settings, themedia, community agencies, academic institutions, and local and state policy-makers [9]. It
included: An innovative media campaign to change public opinion and community norms
 Community mobilization to change local laws and health regulations
 Comprehensive tobacco treatment programmes based in clinics and community
settings.
Example 2. A community-driven research programme with gastric cancer prevention goals
demonstrates how community-engaged research can be part of a multilevel approach todevelop and implement effective prevention strategies. The Canadian North Helicobacter
pylori (CANHelp) Working Group is an intersectoral and interdisciplinary team comprisingcommunity organizations and residents, health-care providers, health technology industry
representatives, and academic researchers. The research programme was initiated afterconcerns were voiced by Aboriginal communities about cancer risk from H. pylori infection.
These communities, located in the Yukon and Northwest Territories of Canada, advocatedfor research to find solutions and were supported by health officials who sought information
to improve health care for H. pylori infection. The research programme uses a collaborativeand participatory approach in pursuit of the following aims:
 To obtain representative data from diverse Arctic communities for developing publichealth strategies for control of H. pylori infection in the circumpolar north.
 To conduct policy analysis to identify cost-effective H. pylori management strategies
that are ethically and cultural appropriate for the target population.
 To develop knowledge exchange strategies that help participating communities
understand H. pylori health risks, available solutions, and unsolved challenges for
reducing these risks.
5. Gaps in the evidence for evidence-based gastric cancer prevention
The Circumpolar H. pylori Working Group (Brian J. McMahon, Michael G. Bruce, Anders
Koch, Karen J. Goodman, Vladislav Tsukanov, Gert Mulvad, Malene L. Borresen, Frank
Sacco, David Barrett, Steven Westby, and Alan Parkinson) has produced a manuscript
entitled “Expert commentary on the diagnosis and treatment of Helicobacter pylori infection
in Arctic regions with a high prevalence of infection”, which reaches the following
conclusions about the adequacy of evidence for evidence-based gastric cancer prevention
strategies: Treatment of H. pylori infection should be limited to conditions for which there isstrong evidence of benefit in terms of reduced morbidity/mortality:o peptic ulcer diseaseo mucosa-associated lymphoid tissue (MALT) lymphoma.
 A test-and-treat strategy for individuals with dyspepsia should not be used in Arctic
regions with high prevalence of H. pylori infection.
o Most individuals in these areas will have been infected during their lifetime.
o Particularly in instances where serology is used to test, most individuals,
whether or not infected, will have a positive test.
92

Evidence shows that: The proportion of individuals treated successfully can be as low as
50%.
 Antimicrobial resistance is high.
 Re-infection rates are high.
 Indications for treatment of H. pylori are inconclusive for individuals with severe
gastritis that is not associated with heavy alcohol consumption or use of non-steroidal
anti-inflammatory drugs; randomized controlled trials are needed to estimate thebenefit of treating such individuals.
 Researching the local costs and benefits of alternative H. pylori management
practices will lead to improvements in the evidence base for local policies.
 Additional studies of the following sort are needed:o Community intervention trials designed for accurate estimation of the effect on
the risk of gastric cancer of screening and treating for H. pylori within
subgroups defined by factors that may modify this effect.
o Studies designed to estimate effects on gastric cancer risk of screening andtreating asymptomatic individuals with a strong family history of gastric cancer.
o Studies to identify bacterial and host factors that may better identify H. pyloriinfected persons who benefit most from treatment.
o

6. Summary and key messages
Prevention strategies should be tailored to the local context because of variation inavailable resources, priorities, intervention costs, and intervention effectiveness(variations in screening accuracy, treatment effectiveness, prevented fraction).
 Pressure to move too rapidly to widespread implementation leads to gaps inevidence of the efficacy, effectiveness, safety, and economic impact of potential
prevention strategies.
 Disease prevention initiatives can be more effective when they expand opportunities
for prevention through partnerships across health systems, communities, academia,
business, and the media.
 Community-engaged research can be part of a multilevel approach to develop andimplement effective prevention strategies.

References
1. Higgs J, Jones M (2000). Will evidence-based practice take the reasoning out of practice?
In: Higgs J, Jones M, editors. Clinical reasoning in the health professions, 2nd ed.
Oxford, UK: Butterworth-Heinemann; p. 311.
2. Rycroft-Malone J, Seers K, Titchen A, Harvey G, Kitson A, McCormack B (2004). Whatcounts as evidence in evidence-based practice? J Adv Nurs. 47(1):81–90.
http://dx.doi.org/10.1111/j.1365-2648.2004.03068.x PMID:15186471
3. Skovgaard T, Nielsen MBD, Aro AR (2007). Evidence in health promotion and disease
prevention 2008. Copenhagen: Danish National Board of Health. Available from:http://sundhedsstyrelsen.dk/Publ/Publ2007/CFF/Evidens_forebyggelse/Evid_Health_Pro
m_jan2008.pdf
4. Brownson RC, Baker EA, Left TL, Gillespie KN, True WR (2011). Evidence-based publichealth, 2nd ed. New York: Oxford University Press.
5. Brownson RC, Gurney JG, Land GH (1999). Evidence-based decision making in publichealth. J Public Health Manag Pract. 5(5):86–97. http://dx.doi.org/10.1097/00124784199909000-00012 PMID:10558389
6. Teutsch SM (1992). A framework for assessing the effectiveness of disease and injury
prevention. MMWR Recomm Rep. 41(RR-3):1–12. PMID:1313535

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7. Greenwald P, Kramer BS, Weed DL (1995). Cancer prevention and control. New York:
Marcel Dekker.
8. World Health Organization (2002). National cancer control programmes: policies andmanagerial guidelines, 2nd ed. Geneva: World Health Organization. Available from:http://www.who.int/cancer/media/en/408.pdf
9. Ockene JK, Edgerton EA, Teutsch SM, Marion LN, Miller T, Genevro JL, et al. (2007).
Integrating evidence-based clinical and community strategies to improve health. Am J
Prev Med. 32(3):244–52. http://dx.doi.org/10.1016/j.amepre.2006.11.007
PMID:17296474 Available from:http://www.uspreventiveservicestaskforce.org/uspstf07/methods/tfmethods.htm

94Chapter 3.2
Potential regimens for the mass eradication of Helicobacter pylori
infection
Javier P. Gisbert and E. Robert Greenberg
It was more than 30 years ago that Helicobacter pylori was discovered and 20 years ago thatstandard triple therapy – a proton pump inhibitor (PPI) plus two antibiotics – was establishedin clinical practice for the eradication of this infection [1]. Nowadays, the efficacy of triple
therapy is seriously challenged in many parts of the world, where eradication rates havedeclined to unacceptably low levels, largely related to development of resistance toclarithromycin [2]. It is this low efficacy that compromises the design and development of any
mass screening and treatment programme for the prevention of gastric cancer. Moreover,
the risk of causing a direct or ecological increase in the existing antibiotic resistance rates of
H. pylori and other agents must be taken into consideration before implementing screening
and treatment programmes.
In this context of mass screening and eradication of H. pylori, the most efficient treatment
regimen may not be the same as for routine clinical management of symptomatic H. pylori
patients. Efficacy must be considered, but other issues affecting the treatment, such as cost,tolerability, and simplicity (and therefore compliance), gain an even more important role [3].
Moreover, design of these programmes must be concerned with the impact they may haveon the selection of antibiotic-resistant strains from H. pylori and other species, at both theindividual level (direct selection of surviving strains) and the societal–ecological level (thetype and quantity of antibiotic compounds entering the ecosystem may increase widespread
resistance).
Programme design and treatment recommendations in H. pylori screening must, therefore,
fit the narrow criteria to be an acceptable compromise between cancer prevention aims
(cost–effectiveness) [4] and infection prevention (mass eradication reduces sources ofinfection), with the containment of antimicrobial resistance [5].
1. The problem of antibiotic resistance: a worldwide perspective
The most common causes for the failure of reliably good or excellent regimens are poor
compliance with therapy and/or the presence of organisms resistant to one or more of theantimicrobial agents used [3, 6]. Several studies have suggested a variety of miscellaneous
factors that might be important in H. pylori eradication, including age, presentation (e.g.
functional dyspepsia vs duodenal ulcer), and CagA status [7, 8]. However, these candidates
have typically been discovered in data-dredging studies in which resistance was notassessed [9].
Resistance rates vary remarkably in different geographical areas, and therefore the selectionof therapeutic regimes needs adjustments according to the local resistance pattern. The
prevalence of antibiotic resistance (mainly to clarithromycin, metronidazole, and levofloxacin)in various regions is correlated with the general use of antibiotics – for infectious diseases
other than H. pylori infection – in the region [10–12]. For example, the long-term use ofclarithromycin as monotherapy, mainly for respiratory tract infections, has led to high H.
pylori clarithromycin resistance rates [10]. This explains why those countries in northern
Europe that have a strict policy for antibiotic use still have a low prevalence of resistance[13]. The resistance against amoxicillin is virtually zero, with few exceptions, and thus it does
not represent a concern for its use in treatment regimens [14].

95A systematic review performed in 2010 analysed the clarithromycin resistance rates indifferent areas around the world [15]. On a global scale, resistance was detected in 17% of
the cases. The resistance rates differed significantly between Europe (11%), Asia (19%),
and the Americas (29%). A recent European multicentre study [12] showed that resistance
rates in Europe for adults were 17% for clarithromycin and 35% for metronidazole. In
Europe, there are also huge differences between geographical areas, mainly between
southern and northern Europe [16]. The same occurs in various regions of Asia, with low
rates in Malaysia and high rates in Japan [16].
2. Tailored versus empirical treatment
Ideally, the treatment for a bacterial infectious disease should be chosen based on culture
and susceptibility testing. Pretreatment H. pylori susceptibility testing allows the selection ofa regimen tailored by antimicrobial susceptibility. However, this is not always feasible in H.
pylori-infected patients because it requires an invasive procedure (i.e. gastroscopy), which
obviously is not indicated in mass programmes such as those aimed at preventing gastriccancer in the general population [4]. Thus, if these programmes are implemented, one must
empirically choose therapy, and in this instance the best approach is to use regimens thathave been proven reliably effective in a given area [9, 17, 18]. That choice should takeadvantage of the knowledge of resistance patterns obtained from local or regional
antimicrobial surveillance programmes and/or based on local clinical experience with regard
to which regimens are effective locally [9]. In the end, the recommendations stated by eachcountry’s guidelines on H. pylori treatment should be followed. Finally, the history of thepatient’s prior antibiotic use and any prior therapies will help identify which antibiotics arelikely to be successful and those for which resistance is probable [9].
As Graham et al. have accurately stated, “All other things being equal, data from any area orregion regarding the effects of resistance on outcome can be used reliably to predict
outcome in any other area” [9]. Thus, strains with similar patterns of resistance in Spain, theUSA, the Islamic Republic of Iran, China, and so forth should be expected to respond alike,so that if one knows the results with susceptible strains and with resistant strains in one
place, one can reasonably predict the outcome of therapy anywhere [9].
In summary, a first-line eradication regimen should be based on what works best in adefined geographical area and must take into account the prevalence of antimicrobial
resistance in that region [18].
3. The importance of compliance with and tolerance of treatment
Compliance is an important issue, mainly when H. pylori treatment is planned to be includedin the context of population-based screening (such as mass programmes to prevent gastriccancer in the general population) rather than clinical management. Furthermore, side-effects
are reported by approximately 50% of patients. Therefore, in this setting, significant effort
should be directed towards identifying a regimen that is short and easy for the patient tofollow [19].
If compliance with the regimen is poor, even the best-designed regimen will have a pooroutcome, so another aspect of optimization is to identify the factors that determine
compliance, such as dosing, duration, and side-effects [20]. The fact that H. pylori therapy
involves multiple drugs (and frequently multiple dosing intervals) makes patient education
extremely important. It is worth considering direct counselling about the regimen and theneed to be compliant, as well as providing handouts with the objectives and the details of theregimen [9]. Measures to enhance compliance improve eradication success and aremeaningful when large numbers of patients are treated. At a minimum, patients should96

receive counselling about the anticipated side-effects and the importance of completing thetreatment regimen [21]. A few extra minutes can prevent most of the issues associated withtreatment failures [20]. In this respect, it is well known that adherence to the therapy is
associated with high eradication rates: patients taking 60% or more of the prescribed therapy
have a higher treatment success compared with patients with a poor compliance (96% vs69%) [22].
Adherence to treatment is a very important consideration, which partially depends on thecomplexity of the therapeutic regimen. For example, the ingestion of multiple medications,
up to 4 times a day in some regimens, can cause problems with adherence. Moreover,confusion may be caused when treatments or drug intake change during the regimen.
4. Standard triple therapy
The triple therapy including PPI–clarithromycin and amoxicillin or metronidazole proposed at
the first Maastricht conference to treat H. pylori infection has become universal since it wasrecommended by all the consensus conferences held around the world [23].
However, the most recent data show that this combination has lost some efficacy and often
allows the cure of only a maximum of 70% of the patients, which is less than the 80% rate
aimed for at the beginning and far below what should be expected for a bacterial infection[2]. In some European countries, the success rates are disappointingly low [24], with valuesof only 25–60% [25, 26]. At present, as a general rule, it has been recommended that aregimen should not be used unless it reliably produces an eradication rate greater than 90%(per-protocol) [20]. An effective (i.e. > 90%) first-line therapy has been considered
mandatory for avoiding supplementary treatments and testing, and more importantly forpreventing the development of secondary resistance. However, desirable qualities of an
optimal regimen may differ between that used to treat “sick” patients (such as ulcer patients),
where eradication effectiveness will be paramount, and that used in mass programmes toprevent gastric cancer in the general population, where compliance, tolerance, ease, cost,and avoiding the emergence of resistance will be important.
There are several explanations for the decrease in efficacy of the standard triple therapy:
compliance, high gastric acidity, high bacterial load, and type of strains, but by far the mostimportant is the increase in H. pylori resistance to clarithromycin. Pooled data from 20
studies involving 1975 patients treated with standard triple therapy showed an eradication
rate of 88% in clarithromycin-sensitive strains versus only 18% in clarithromycin-resistantstrains [10].
The global clarithromycin resistance rate in Europe increased from 9% in 1998 [27] to 18%
in 2008–2009 [12]. Resistance has increased in most parts of Europe, but it has now
reached a prevalence of greater than 20% in most countries in central, western, andsouthern Europe, which is considered a high resistance rate. In northern European
countries, prevalence is less than 10%, which is considered a low resistance rate [14].
Following the European Medicines Agency recommendation on evaluation of medicinal
products indicated for treatment of bacterial infection, three categories of bacterial species
can be defined, according to their susceptibility to a given antibiotic: usually susceptible (0–10% resistant), inconstantly susceptible (10–50% resistant), and usually resistant (> 50%
resistant). H. pylori now falls into the second category for clarithromycin resistance, except innorthern Europe and Thailand [28].
To take into account the confidence intervals of the prevalence obtained and the regional
differences in a given country, a threshold of 15–20% was recommended to separate theregions of high and low clarithromycin resistance. Thus, in areas with clarithromycin
resistance of less than 10–15% (i.e. the Netherlands, Sweden, Ireland, Germany, Malaysia,
97and the south of Taiwan, China), it is still possible to use the standard triple therapy toachieve a per-protocol eradication rate greater than 80–90% [18]. Accordingly, it has beenstated (e.g. Maastricht IV conference) that “in areas of low clarithromycin resistance,clarithromycin-containing treatments are recommended for first-line empirical treatment(although bismuth-containing quadruple therapy is also an alternative)” [23]. However, it wasstated that “PPI–clarithromycin-containing triple therapy without prior susceptibility testingshould be abandoned when the clarithromycin resistance rate in the region is more than 15–20%” [23].
In case the clarithromycin-containing triple regimen is selected to be used as the first-line
treatment, different ways of improving its efficacy have been proposed. These are outlined
below.
4.1 Increasing the dose of PPIThere is indirect and direct evidence that high-dose PPI can improve the cure rates of H.
pylori treatment. Indirect evidence comes from old multiple studies showing that high-dose
PPI was necessary for the efficacy of dual therapies and the meta-analysis showing thattwice-a-day PPI was better than a single daily dose in triple therapy [29]. Direct evidence
comes from a meta-analysis showing that high-dose PPIs increase cure rates by about 6–
10% compared with standard doses [30]. A subanalysis of these data showed that the
maximal effect was seen in the studies comparing high doses of the more potent secondgeneration PPIs (i.e. 40 mg of esomeprazole twice a day) with a standard dose of a first-line
PPI, also twice a day [30]. The rationale for this finding is that the difference in the degree ofgastric secretion between arms is more important when using double doses of more potent
PPIs. According to the data of that subanalysis, increasing the dose of PPI from, forexample, 20 mg of omeprazole twice a day to 40 mg of esomeprazole or rabeprazole twice a
day may increase cure rates by 8–12% [30].
PPIs undergo hepatic metabolism mainly via the cytochrome P450 (CYP) pathways and theisoforms CYP2C19. There are interindividual differences in the activity of CYP2C19, which
may affect the pharmacokinetic behaviour and clinical efficacy of PPIs [31, 32]. Indeed, theCYP2C19 phenotype is categorized into three groups: extensive or rapid metabolizer,
intermediate metabolizer, and poor metabolizer. The proportion of CYP2C19 rapid
metabolizers was proven to be higher in Europe and in North America, whereas the
proportion was lower in the Asian population [33]. Significantly higher eradication rates of H.
pylori have been observed in patients with the poor or intermediate metabolizer phenotype,compared with extensive metabolizers [34]. Thus, initial genotyping for this enzyme would be
ideal before H. pylori therapy, since higher dosage in extensive metabolizers is likely to
improve the clinical efficacy of PPIs for H. pylori therapy. Obviously, this approach isunrealistic in clinical practice, so it is conceivable that all patients, especially in Europe andNorth America, should receive high-dose PPI therapy to circumvent the high rate of
CYP2C19 rapid metabolizers.
Finally, as for the different available PPI molecules, a recent meta-analysis disclosed thatthe efficacy of omeprazole- and lansoprazole-based first-line triple therapies at the standard
doses was dependent on CYP2C19 genotype status, which appeared not to affect theefficacy of the regimens including rabeprazole [35]. In line with this finding, two other recent
meta-analyses have demonstrated that esomeprazole and rabeprazole provide better overall
H. pylori eradication rates, especially in CYP2C19 extensive metabolizers [36, 37].
4.2 Increasing the duration of treatment
Several meta-analyses have been carried out and have yielded very similar results: a 10-day
treatment improves the eradication rate by 4%, and a 14-day treatment improves theeradication rate by 5–6%, compared with a 7-day treatment [38–40]. More recently, a98Cochrane review confirmed that, in general, increasing the duration of PPI-based triple
therapy increases H. pylori eradication rates, and that specifically for a PPI–clarithromycin–
amoxicillin regimen, prolonging the treatment duration from 7 days to 10 days or from10 days to 14 days is associated with a significantly higher eradication rate; thus, the optimal
duration of therapy for this regimen was considered to be 14 days [41].
With 14-day therapy, the combination remains effective until clarithromycin resistanceexceeds approximately 15%, whereas 7-day therapy is compromised by clarithromycin
resistance that exceeds 5%. Currently, there are few regions in the world whereclarithromycin resistance is less than 15% (i.e. the 14-day regimen is still useful in suchareas as northern Europe and Thailand) [9].
Although the difference in efficacy between short and long regimens is statisticallysignificant, it may be considered relevant or not, according to other factors such as cost,
mainly when the perspective of mass eradication in large populations is considered.
Furthermore, although some authors have reported a benefit of prolonging the duration of
triple therapy, others – from the Republic of Korea [42] and Turkey [43] – could notdemonstrate an advantage for this strategy. Thus, prolonging H. pylori triple therapy seems
to increase – overall – eradication rates, but whether it represents a clinically useful strategy
should be locally evaluated.
4.3 Using metronidazole instead of amoxicillin as the second antibiotic
The Achilles heel of metronidazole-containing triple therapy is metronidazole resistance, andmetronidazole-containing triple therapy now rarely is used except as a tailored therapy or inJapan, where the general use of metronidazole has been strongly discouraged by thegovernment because of possible genotoxicity [9]. In any case, a previous meta-analysis [44],updated for the Maastricht IV conference, did not find statistically significant differences in
eradication rates for PPI–clarithromycin–metronidazole (71%) and for PPI–clarithromycin–
amoxicillin (65%) when the same dose of clarithromycin was used [23].
5. Bismuth-containing quadruple therapy
From a microbiological standpoint, the most rational way to overcome antibiotic resistancewould be the use of a combination of drugs for which resistance does not appear to be a
problem, so, as previously mentioned, no clarithromycin-based regimens should berecommended in geographical areas with increasing clarithromycin resistance rates. In thiscontext, bismuth-containing quadruple therapy (PPI, bismuth, metronidazole, andtetracycline) seems to be an attractive alternative treatment [13]. Accordingly, bismuthcontaining quadruple therapy has been recommended by the Maastricht IV Consensus
Report [23] and by the Second Asia-Pacific Consensus Guidelines for H. pylori infection [45]as an alternative first-choice regimen to standard triple therapy in areas with a low rate ofclarithromycin resistance, and has been recommended as the first-line therapeutic option inareas with a high prevalence of clarithromycin resistance.
As Mégraud has accurately stated, in the context of increased resistance to antibiotics,
quadruple therapy has the advantage of using the following compounds [13]: (i) bismuth,
whose mechanism of action appears to be more like an antiseptic than an antibiotic, and forwhich no resistance has been described; (ii) tetracycline, an antibiotic for which resistance israrely encountered; and (iii) metronidazole, for which resistance in vitro exists at a highprevalence in most countries around the world, but the clinical impact of this resistance islimited and it can be overcome by increasing the dose and duration of treatment (in addition,
the quadruple regimen overcomes clarithromycin resistance). Thus, if this quadruple
regimen is used at full doses and for 14 days, one can expect greater than 90% treatment
success irrespective of the level of metronidazole resistance [46–48]. Indeed, a meta-99

analysis of 91 treatment arms concluded that if nitroimidazole resistance is present, a
nitroimidazole-containing regimen should be avoided or a quadruple regimen should begiven for more than 1 week [49]. Therapy for 7 days, and probably for 10 days, is very
susceptible to metronidazole resistance [46]. Accordingly, it has been recommended that the
duration be 14 days whenever metronidazole resistance is known or suspected [20].
Several meta-analyses comparing the outcomes of triple therapy and bismuth-containing
quadruple therapy found similar eradication rates for both regimens when used as first-line
therapies for H. pylori infection [50–52]. However, many of these comparative studies
predate the emergence of high rates of clarithromycin resistance.
Bismuth-containing quadruple therapy is the treatment most in need of clinical trials to
simplify the regimen to improve compliance. Recent studies in China have shown that twicea-day bismuth may be sufficient [48, 53]. Furthermore, studies in Italy have suggested thattwice-a-day therapy (at the noon and evening meals) may be sufficient, which would allow
the total dosage to be cut in half, likely with improved compliance [54, 55].
Recently, a novel bismuth-containing quadruple therapy using a single three-in-one capsulecontaining bismuth subcitrate, metronidazole, and tetracycline has been proposed todecrease the pill burden and improve patient compliance. The value of this regimen is basedon two randomized clinical trials, one performed in North America [56] and the other inEurope [57], where the three-in-one capsule treatment was compared with the standard
regimen of omeprazole, amoxicillin, and clarithromycin. The intention-to-treat results in the
North American trial were 86% for the bismuth-containing regimen and 80% for the standard
triple regimen; for the European trial, they were 80% and 55%, respectively. The apparent
lower success rate in the European trial can be linked to protocol violations. In contrast to
many other trials, the protocol was very stringent in requesting two negative urea breath
tests at a 1-month interval. Unfortunately, some missing second urea breath test results led
these cases to be considered as failures. Considering one urea breath test result instead oftwo, the eradication rate was 93% for the bismuth-containing quadruple regimen versus 68%
for the standard triple regimen. Finally, it should be emphasized that despite the high level ofmetronidazole resistance in both trials, this did not influence the results significantly.
It is interesting to look at the difference between the eradication rates of a clarithromycinbased regimen versus a bismuth-based regimen in the two trials: 6% in the North American
trial and 25% in the European one [13]. One possible explanation may be the difference induration of treatment (7 days in Europe and 10 days in North America). However, the most
likely reason appears to be the higher resistance to clarithromycin in Europe than in North
America between the two trials carried out 10 years apart [13].
Another international multicentre study, which was not a comparative trial, was carried out toevaluate the impact of metronidazole in vitro resistance on the efficacy of three-in-one
capsule treatment in vivo [58]. A total of 170 patients were included, and the metronidazole
resistance rate was 33%. The overall eradication rate by modified intention-to-treat was
93%, with no significant difference between metronidazole-resistant cases (93%) andmetronidazole-susceptible cases (95%).
The safety and tolerability of the quadruple therapy, which is still one of the unjustified
concerns about the quadruple therapy, have been similar to those of the standard triple
therapy in several meta-analyses [50–52]. Regarding safety, in the context of H. pylori
eradication, the doses of bismuth currently used in the quadruple regimen are relatively low
and are administered for a short time period, leading to blood levels lower than 50 mg/L,
considered to be at the threshold for potential bismuth toxicity [59].

100Finally, because the bismuth-containing quadruple therapy is an inexpensive regimen, it isoften preferred in situations where the cost of therapy is the main concern, which may be thecase for mass programmes in the general population. However, limitations of this quadruple
regimen are the unavailability of bismuth salts worldwide, and the fact that many countries
are currently also experiencing a general unavailability of tetracycline.
6. Non-bismuth-containing quadruple therapies“Sequential” treatment consists of the administration of a 5-day induction phase ofamoxicillin plus PPI followed by 5 days of PPI, clarithromycin, and metronidazole (all given
twice a day) [60, 61]. “Concomitant” treatment combines these four drugs given together forat least 10 days [62–64]. Although non-bismuth-containing quadruple therapy is not ideal
because it contains clarithromycin, it has been shown that clarithromycin resistance could beovercome in several cases. Indeed, the success rate of non-bismuth-containing quadruple
therapies with clarithromycin-resistant strains was relatively high [60]. Thus, non-bismuthcontaining quadruple schemes have been recommended as first-line therapy in areas withhigh clarithromycin resistance (> 15–20%), mainly where bismuth-containing quadruple
therapy is not locally available [23].
6.1 Sequential therapy
Sequential therapy was developed in Italy in 2000 as a replacement for triple therapy [65,66]. Until 2008, most of the studies on this therapeutic strategy had been conducted in Italy.
In 2007, a randomized controlled trial showed a significant advantage of 10-day sequential
therapy over 10-day triple therapy (eradication rate, 91% vs 78%), and the sequential
therapy was highly effective against clarithromycin-resistant strains [67]. A pooled data
analysis with evidence from Italian studies showed promising eradication rates higher than
90%, even in patients with risk factors for failure of triple therapy (clarithromycin or
metronidazole resistance, functional dyspepsia, smoking, or the absence of the CagA gene)[68]. Indeed, several meta-analyses evidenced the advantage of sequential therapy over
triple therapy [69–71]. Accordingly, it was suggested in 2007 by the American College of
Gastroenterology Guidelines [72] and the European Maastricht Consensus (Maastricht III)[73], as well as in 2009 by the Second Asia-Pacific Consensus Guidelines [45], thatsequential therapy was a promising therapy, but it required further evaluation outside Italy
before a generalized change in first-line H. pylori treatment was recommended.
In 2010, a critical review of the published evidence highlighted several concerns in previous
meta-analyses, such as lack of validation outside of Italy, low-quality studies, or insufficient
information on the effect on antibiotic-resistant strains [60]. In 2011, a large, multicentre trialfrom Latin America showed no advantage of 10-day sequential therapy over 14-day triple
therapy [74]. In 2012 and 2013, an updated meta-analysis in children and two systematic
reviews in adults dealing with sequential therapy were published [75–77]. From 2008 to
2013, cure rates of sequential therapy in studies conducted in Asia, Europe, and Latin
America remained significantly better than those of triple therapy, but mean eradication rates
dramatically dropped by 15% compared with those in Italian trials before 2008. A recent
multicentre study performed in Taiwan, China, comparing 14-day sequential and triple
therapy definitely showed the limitations of sequential therapy, since the efficacy of thisregimen was impaired by both clarithromycin and metronidazole resistance [78]. Finally, a
recent meta-analysis showed a mean cure rate of 84% for 10-day sequential therapy, which
was superior to that of 7-day triple therapy and marginally superior to that of 10-day triple
therapy but not superior to that of 14-day triple therapy [61]. Currently, 10-day sequential
therapy cannot be considered a good therapeutic option to overcome antibiotic resistance,
and its failure might be expected when the prevalence of dual – clarithromycin plus
metronidazole – resistant strains is greater than 5%.

101

6.2 Concomitant therapy
The term “concomitant” therapy, which implies that all the antibiotics are administered
together, is actually a misnomer because all treatments for H. pylori, with the exception ofsequential therapy, are in fact concomitant therapies, but this will be the term used hereafter
as it has been widely used. The concept of this regimen consists of converting standard
triple therapy to a quadruple therapy by the addition of 500 mg of metronidazole or tinidazole
twice a day. In 1998, two groups of investigators, one in Germany and the other in Japan,
proposed that a PPI, amoxicillin, clarithromycin, and nitroimidazole be given concurrently as
a four-drug, three-antibiotic, non-bismuth-containing quadruple regimen [79, 80]. Despite theshort duration of therapy (5 days on average), this approach provided, at that time, high curerates (90% by intention-to-treat). It fell into oblivion after a few years of research, but
resurfaced in 2010 as an alternative therapy to triple and sequential therapy [63, 64].
Meta-analyses have shown that the outcome of concomitant therapy is duration-dependent[63, 64], which was confirmed in a recent head-to-head comparison of 5-day and 10-day
concomitant therapies in Thailand, where 5-day therapy proved unsatisfactory [81], and by
failure of 5-day concomitant therapy in Latin America [74] and the Republic of Korea [82]. In
a recent study, 14-day concomitant therapy achieved the best intention-to-treat results (92%)[83] compared with studies evaluating 10-day concomitant therapy (86–87%) [84, 85].
Finally, it has recently been demonstrated that a 14-day high-dose concomitant regimen ishighly effective for H. pylori eradication, achieving cure rates greater than 90% both by perprotocol and by intention-to-treat, and that this optimized regimen is more effective than thestandard (10-day) one [86].
The Achilles heel of concomitant therapy is dual metronidazole–clarithromycin resistance.
Thus, the efficacy of concomitant therapy was not impaired by either clarithromycin or
metronidazole isolated resistance, but it is expected to fall below 90% when the prevalenceof dual clarithromycin–metronidazole-resistant strains is greater than 15% [9]. Accordingly,
concomitant therapy may be the preferred initial empirical therapy for areas and patientgroups in which dual resistance is unlikely but is not recommended as a first-line empiricalregimen where metronidazole resistance is likely greater than 60%, such as China, theIslamic Republic of Iran, India, or Central and South America, or in populations at high risk ofdual resistance (i.e. after clarithromycin or metronidazole treatment failures) [9]. These
recommendations are in agreement with suboptimal results in Latin America [74], theRepublic of Korea [82, 87], and Turkey [88], where clarithromycin-resistant, but especiallymetronidazole-resistant, H. pylori strains are very prevalent. Likewise, they match with good
to excellent results in southern Europe and some Asian countries, where rates ofclarithromycin resistance range from low (9%) to high (40%) figures but metronidazole
resistance remains in relatively low figures (< 30–40%).
If a non-bismuth-containing quadruple regimen is going to be used, a relevant question iswhether a sequential or a concomitant regimen should be preferred. Recently, several
studies have evaluated the efficacy of sequential and concomitant non-bismuth-containing
quadruple therapies against clarithromycin- and metronidazole-resistant strains.
Georgopoulos et al. addressed this issue nicely [89], and their results have been adapted[90] to exhibit the most recent evidence [83, 84, 91–93]. Concomitant and sequential
therapies were successful against dual-resistant strains in 78% (18 of 23) and 33% (9 of 27)of the cases, respectively. Furthermore, a recent meta-analysis comparing sequential andconcomitant therapy has shown a significant advantage of concomitant therapy [94]. Overall,solid evidence points towards concomitant therapy being a more reasonable therapeutic
option in areas with a high incidence of clarithromycin and/or metronidazole resistance [89],but, as previously stated, it is expected to fail when the prevalence of dual clarithromycin–
metronidazole-resistant strains is greater than 15% [9]. Finally, it should be taken into102

account that concomitant therapy is less complex than sequential therapy, as theconcomitant regimen does not involve changing drugs halfway through.
6.3 Treatment as an ecological/societal factor for future resistance
The societal consequences of the massive use of antibiotics should also be taken into
account, as a positive correlation between antibiotic consumption and bacterial resistance tothe corresponding antibiotic, as well as a negative impact on the normal flora (microbiota),
has been reported [95]. Studies performed in Sweden have shown the impact of thestandard clarithromycin-based triple therapy on the resistance of some bacteria present in
the flora from saliva and intestine [95]. Samples showed an increase in amoxicillin minimum
inhibitory concentrations (MICs) for Streptococcus sp., Staphylococcus sp., andEnterococcus sp., and an increase in clarithromycin MICs also for Enterobacteriaceae andBacteroides sp., whereas a suppression of other anaerobic bacteria occurred. Persistence ofhigh-level clarithromycin-resistant enterococci was found for 3 years in 3 of 5 patients in along-term follow-up [96, 97]. Thus, when mass eradication in large populations is
considered, it should be taken into account that the ecological impact of regimens such as
the non-bismuth-containing quadruple regimens – which involve simultaneous administrationof three broad-spectrum antibiotics such as amoxicillin, clarithromycin, and metronidazole –can be expected to be quite negative, with the selection of multiresistant strains despite aheavy antibiotic load received by the patients [13]. The acquired resistances in thesepatients may become a major societal concern as they, in turn, become infection sources,
spreading the resistant strains. Finally, the ecological burden of antibiotic waste into theenvironment, both from unused pills and from excretion by the treated patient, may increase
the appearance and selection of resistant strains [98].
7. Conclusion
In summary, a treatment recommendation to follow a H. pylori screening programme musttake into consideration several factors, such as cost–effectiveness, simplicity, safety, direct
selection of resistance, and ecological impact. Although a wide screening programme willprobably have to recommend different regimens for different areas, bismuth-containing
quadruple therapy positions itself as the most viable candidate in most regions.

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110Chapter 3.3
Feasibility and cost–effectiveness of population-based
Helicobacter pylori eradication
Paul Moayyedi
Wilson and Jungner described a classic set of criteria for a successful screening programme[1], and it has previously been shown that Helicobacter pylori screening and treatment toprevent gastric cancer fulfils most of these conditions [2]. This chapter focuses on whether apopulation H. pylori test-and-treat strategy (i.e. testing for the bacterium non-invasively andtreating infected individuals) is likely to be feasible and cost-effective.
1. Feasibility of population H. pylori test and treat
For a screening programme to be feasible, there must be a diagnostic test and a therapy
that is affordable and acceptable to the population. Facilities should be available to conduct
a population H. pylori test-and-treat strategy; the diagnostic test should be accurate and thetreatment effective. Population H. pylori test and treat fulfils these criteria when comparedwith other screening programmes that are currently available in most developed countries,
such as cervical cancer screening [3] and colorectal cancer screening [4].
The most readily available test for H. pylori is serology. This is inexpensive, and many
commercial kits are available [5]. The infrastructure needed to administer this test is in placein most countries as serology is widely used for a variety of medical investigations. The test
is likely to be acceptable to the population as people are used to undergoing blood tests.
Screening projects such as prostate-specific antigen testing to screen for prostate cancer [6]have not found a blood test a barrier to recruitment. The median sensitivity for commercial H.
pylori serology tests is more than 90% and the median specificity greater than 80% [7]. This
is not ideal but is acceptable for a population screening programme. If greater accuracy isneeded, then the stool antigen test has sensitivities and specificities greater than 95% [8].
Subjects in most countries may find stool samples less pleasant to deal with than providing aserum sample, but faecal occult blood testing programmes have been instituted in the United
Kingdom and Canada to detect early colorectal cancer, without any major problems [9].
Stool antigen tests are more expensive than serology and are therefore likely to be less costeffective than serology. Carbon urea breath tests (UBTs) have also been used in screening
studies [10]; although these are the non-invasive gold standard in terms of accuracy [11, 12],the 13C-UBT is expensive and the 14C-UBT involves exposing the person being screened toradiation (although at one tenth of the dose needed for a chest X-ray). Overall, most haveconsidered that serology is the most cost-effective and acceptable test to use in a screening
programme [13].
The therapy most commonly used to treat H. pylori infection is a proton pump inhibitor (PPI)
combined with clarithromycin and either amoxicillin or metronidazole, each given twice a day
for 1–2 weeks – so-called PPI–clarithromycin-based triple therapy. Initial reports suggested
that these regimens would eradicate the infection in more than 90% of cases [14], but overtime eradication rates have fallen, and now this regimen often achieves rates below 80%,
possibly due to the increased prevalence of clarithromycin resistance. Another alternative isbismuth salts combined with tetracycline, PPI, and metronidazole for 1 or 2 weeks – socalled quadruple therapy. This achieves eradication rates in excess of 80% [15], andmetronidazole resistance has only a modest impact on efficacy. Both types of regimen aretolerable, and PPI triple therapy has the advantage of being simple to take. Quadruple
therapy is more complex, and in the context of a population eradication strategy this could111be a major concern. In addition, bismuth salts are not widely available worldwide. Morerecently, non-bismuth quadruple regimens, administered either sequentially or
concomitantly, have been demonstrated to be more effective than the standard triple therapy[16, 17].
Currently, therefore, H. pylori screening and treatment is certainly feasible. However, work isneeded to establish the best test and the most appropriate therapy to apply.
2. Cost–effectiveness of population H. pylori test and treat
A screening programme also needs to be affordable, and the benefits of the strategy mustjustify the costs. In 1996, Parsonnet et al. first reported a health economic model thatsuggested population H. pylori test and treat could be a cost-effective strategy to prevent
gastric cancer [18]. This chapter reviews the literature on health economic models publishedsince then that have evaluated population H. pylori screen-and-treat programmes comparedwith “do nothing”, with a view to reducing mortality from gastric cancer. The search strategy
that was used to identify studies is given in Annex 1.
Nine eligible studies were identified [18–26], and the model methodology and results are
summarized in Tables 3.3.1 and 3.3.2. The models studied a variety of populations andmade different assumptions, but all found population H. pylori screening and treatment to becost-effective using a threshold of US$ 50 000 per life-year saved. Most studies evaluatedscreening using serology, and the three that also assessed the carbon UBT all found thisapproach to have an unacceptable incremental cost–effectiveness ratio compared withserology [22, 23, 26]. Most studies also assessed PPI triple therapy as the treatment ofchoice for H. pylori infection, although one evaluated bismuth-based quadruple therapy [26].
All studies also found this result to be robust to the majority of reasonable assumptions andthe main determinants of cost–effectiveness related to the efficacy of eradication therapy toprevent gastric cancer. Models usually made the assumptions from previous systematic
reviews of case–control studies, and none evaluated evidence from systematic reviews of
randomized controlled trials. Savings related to dyspepsia were rarely considered in thesemodels, and none of the studies used data from randomized controlled trials.

112

Table 3.3.1. Summary of economic models that have evaluated population Helicobacter pylori screening and treatment to prevent gastric cancer
Reference

Country

Perspective
taken

Population

Durationof followup

H. pylori
test
evaluated

H. pylori
eradication

Factors
important inmodel

Costeffective?

ICER

18

USA

Third-party
payer

Three ethnic
groups in USA(White, African
American,Japanese) at
age 50–54 years (basecase)

Lifetime

Serology

PCM

Age at whichscreened,
prevalence ofgastric cancer,
efficacy inpreventing
gastric cancer(base case 30%
RRR)

Yes

US$ 25 000

19

USA

Third-party
payer

USA at age 50–
54 years (alsolooked at othercountry data)

Lifetime

Serology,treat CagApositive
only

PCM

Age at whichscreened,
prevalence ofgastric cancer,
efficacy inpreventing
gastric cancer(base case 30%
RRR)

Yes (but nomore thanregularserology)

US$ 23 900

20

USA

Third-party
payer

White men atage 40 years(also African
American,Hispanic, andJapanese)

Lifetime

Serology

UnclearAge at whichscreened,
prevalence ofgastric cancer,
efficacy inpreventing
gastric cancer(base case
RR = 3.6)

Yes

US$ 6264

ICER, incremental cost–effectiveness ratio; LYS, life-year saved; PCA, PPI–clarithromycin–amoxicillin; PCM, PPI–clarithromycin–metronidazole; PPI, proton pumpinhibitor; QALY, quality-adjusted life-year; RR, relative risk; RRR, relative risk reduction; UBT, urea breath test; WTP, willingness to pay.

113

Table 3.3.1. Summary of economic models that have evaluated population Helicobacter pylori screening and treatment to prevent gastric cancer(continued)
Reference

Country

Perspective
taken

Population

Durationoffollowup

H. pylori
test
evaluated

H. pylori
eradication

Factors
important inmodel

Costeffective?

ICER

21

UnitedKingdom

Third-party
payer

UnitedKingdom atage 40–49 years

Until age
85 years

Serology

PCM

Prevalence ofgastric cancer,
efficacy inpreventing
gastric cancer(base case 30%
RRR), savings
related todyspepsia costs

Yes

Dominant(saves US$ 9
per person
screened and130 LYS per
5
10 people
screened)

22

UnitedKingdom

UnitedKingdom atage 40–49 years

Lifetime

Serology(and UBT)

PCM

Efficacy inpreventing
gastric cancer(base case 30%
RRR), savings
related todyspepsia

Yes

US$ 8800

23

Singapore

SingaporeanChinese atage 40 years

Lifetime

Serology(and UBT)PCAPrevalence ofgastric cancer,
efficacy inpreventing
gastric cancer(base case
RR = 3.6)

Yes

US$ 25 881(5700–
120 000)

Third-party
payer

75% certain
cost-effective
at US$ 50 000
threshold

ICER, incremental cost–effectiveness ratio; LYS, life-year saved; PCA, PPI–clarithromycin–amoxicillin; PCM, PPI–clarithromycin–metronidazole; PPI, proton pumpinhibitor; QALY, quality-adjusted life-year; RR, relative risk; RRR, relative risk reduction; UBT, urea breath test; WTP, willingness to pay.

114

Table 3.3.1. Summary of economic models that have evaluated population Helicobacter pylori screening and treatment to prevent gastric cancer(continued)
Reference

Country

Perspective
taken

Population

Durationoffollowup

H. pylori
test
evaluated

H. pylori
eradication

Factors
important inmodel

Costeffective?

ICER

24

Taiwan,China

Societal

Residents of
Matsu Islands
betweenChina andTaiwan,China

Lifetime

UBT

PPI triple
therapyAge at whichscreened,
prevalence ofgastric
cancer,efficacy inpreventing
gastric
cancer (basecase 30%RRR)

Yes

US$ 17 044

25

China

Third-party
payer

Chinese atage 20, 30, or
40 years

Lifetime

Serology

UnclearUnclear what
RRR of H.
pylori
eradication toprevent
gastric
cancerYes< US$ 1600/LYS
for each scenario

26

CanadaThird-party
payer

SingaporeanChinese atage 40 years

Lifetime

Serology(positivestool
antigenand UBT)

Bismuthbased
quadruple
therapy

Prevalence ofgastric
cancer,efficacy inpreventing
gastric
cancer (basecase
RR = 3.6)

Yes

US$ 33 000(stool antigen test
most cost-effective→ 95% certain thatscreening costeffective if WTP
US$ 40 000 per
QALY gained)

ICER, incremental cost–effectiveness ratio; LYS, life-year saved; PCA, PPI–clarithromycin–amoxicillin; PCM, PPI–clarithromycin–metronidazole; PPI, proton pumpinhibitor; QALY, quality-adjusted life-year; RR, relative risk; RRR, relative risk reduction; UBT, urea breath test; WTP, willingness to pay.

115

Table 3.3.2. Summary of the methodology of economic models for population Helicobacter pylori
screening and treatment to prevent gastric cancer
Reference

Type
of
model

Systematic
review ofliterature?

Discounting

Method ofincorporating
uncertainty

Type ofanalysis

Dyspepsia
cost savings
considered?

18

Markov

No

3%

One-way
sensitivity
analysis

C/LYS

No

19

Markov

No

3%

One-way
sensitivity
analysis

C/LYS

No

20

Markov

No

3%

One-way
sensitivity
analysis

C/LYS

No

21

Markov

No

5%One- and twoway sensitivity
analyses

C/LYS

Yes

22

DES

No

6%

Probabilistic

C/LYS

Peptic ulcer
only

23

Markov

No

3%

Probabilistic

C/QALYNo

24

Markov

No

3%

Probabilistic

C/LYS

No

25

Markov

No

3%

One-way
sensitivity
analysis

C/LYS

No

26

Markov

No

3%

Probabilistic

C/QALYNo

C, cost; DES, discrete event simulation; LYS, life-year saved; QALY, quality-adjusted life-year.

Two randomized controlled trials have evaluated the reduction in dyspepsia in H. pyloripositive subjects randomized to eradication therapy or placebo in the context of a population
screen-and-treat strategy [10, 27]. Both studies were in the United Kingdom in approximately
3900 subjects, and each showed a significant reduction in dyspepsia symptoms in thoserandomized to eradication therapy at 2 years, with overall 25% reduction in odds (Fig. 3.3.1).
Interestingly, neither study showed an increase in reflux symptoms [10, 28]. This is importantas some studies have suggested that H. pylori eradication may increase the risk of gastrooesophageal reflux, and this would be a major concern for a population screen-and-treat
programme.

116Fig. 3.3.1. Impact of population Helicobacter pylori screening and treatment on dyspepsia after
2 years. Data are from two studies in the United Kingdom, one in Leeds (Moayyedi et al. (2000) [10])and one in Bristol (Lane et al. (2006) [27]).

Summary meta-analysis plot [random effects]

Leeds

0.78 (0.63, 0.96)

Bristol

0.71 (0.56, 0.90)

combined

0.75 (0.64, 0.88)

0.5

1
odds ratio (95% confidence interval)

Favours H. pylori eradication

Favours placeboThis reduction in dyspepsia is likely to translate into lower health-service-related dyspepsia
costs. The first of the above-mentioned studies reported that H. pylori screening andtreatment given to subjects aged 40–49 years was cost saving at 10 years due to reduction
in dyspepsia costs associated with the strategy [29]. The other population H. pylori screening
and treatment trial, evaluating a wider age range of subjects, also found that H. pyloripositive subjects randomized to eradication therapy had a significantly lower number ofprimary care visits for dyspepsia [30]. It is important to emphasize that savings related todyspepsia in the community have not often been considered in cost–effectiveness models,and none have used data from randomized controlled trials. Considering these cost savings
may make such programmes even cheaper and mean that population H. pylori screening
and treatment could be cost-effective in a wide variety of settings. Another aspect that has
not been considered is the health benefits of population screening and treatment in terms of
prevention of morbidity and mortality from bleeding peptic ulcer [31]. This, again, is likely tomake any population H. pylori screening and treatment programme even more costeffective.
Other limitations of the current health economic literature are that less than half of studies
conduct a probabilistic analysis to evaluate the uncertainty in the data modelled, and evenfewer present the data in a way that is meaningful to health-care decision-makers. One
study that did present the data in this way reported that there is 75% certainty that
population H. pylori screening and treatment is cost-effective for the Singaporean Chinese
population using a threshold of US$ 50 000 per life-year saved [23]. This type of analysis isneeded for other populations using other assumptions relevant to local populations. Most
models evaluated screening programmes from a third-party payer’s perspective. Although
this is a valid approach, it could be argued that societal costs are more important for a117

national screening programme. One economic model did take this perspective and also
found population H. pylori screening and treatment to be cost-effective [24]. Finally, it isimportant to emphasize that nearly all models reported benefit in terms of life-years saved.
This will overestimate the benefit of the programme as most of the life-years saved will be in
the elderly, many of whom have other comorbidities that may limit their quality of life. The
standard economic approach to this problem is to evaluate benefit in terms of qualityadjusted life-years (QALYs). Two studies, with similar methodologies and the same researchteam, did report benefit in terms of QALYs and did find population H. pylori test and treat
cost-effective in both Singapore and Canada [23, 26]. Assigning QALYs at a given age canbe a challenge as data in some populations are lacking, but this approach should be used
more in modelling exercises in this area.
3. Conclusion
Current data would suggest that population H. pylori screening and treatment is feasible andcost-effective in preventing gastric cancer. Future economic models should use current
systematic review data on the efficacy of H. pylori eradication to prevent gastric cancer.
These models should also incorporate health-care-related savings due to dyspepsia
reduction in the population and should assess health benefits in terms of QALYs.
Uncertainty in the data should be evaluated using probabilistic analyses, and there is nomodel currently published that fulfils all these criteria.

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http://dx.doi.org/10.1001/archinte.159.2.142 PMID:9927096
21. Mason J, Axon AT, Forman D, Duffett S, Drummond M, Crocombe W, et al.; Leeds
HELP Study Group (2002). The cost-effectiveness of population Helicobacter pylori
screening and treatment: a Markov model using economic data from a randomized
controlled trial. Aliment Pharmacol Ther. 16(3):559–68. http://dx.doi.org/10.1046/j.13652036.2002.01204.x PMID:11876711
22. Roderick P, Davies R, Raftery J, Crabbe D, Pearce R, Bhandari P, et al. (2003). The
cost-effectiveness of screening for Helicobacter pylori to reduce mortality and morbidityfrom gastric cancer and peptic ulcer disease: a discrete-event simulation model. HealthTechnol Assess. 7(6):1–86. PMID:12709294
23. Xie F, Luo N, Blackhouse G, Goeree R, Lee HP (2008). Cost-effectiveness analysis of
Helicobacter pylori screening in prevention of gastric cancer in Chinese. Int J Technol
Assess Health Care. 24(1):87–95. http://dx.doi.org/10.1017/S0266462307080117
PMID:18218173
11924. Lee YC, Lin JT, Wu HM, Liu TY, Yen MF, Chiu HM, et al. (2007). Cost-effectivenessanalysis between primary and secondary preventive strategies for gastric cancer. Cancer
Epidemiol Biomarkers Prev. 16(5):875–85. http://dx.doi.org/10.1158/1055-9965.EPI-060758 PMID:17507609
25. Yeh JM, Kuntz KM, Ezzati M, Goldie SJ (2009). Exploring the cost-effectiveness of
Helicobacter pylori screening to prevent gastric cancer in China in anticipation of clinical
trial results. Int J Cancer. 124(1):157–66. http://dx.doi.org/10.1002/ijc.23864
PMID:18823009
26. Xie F, O’Reilly D, Ferrusi IL, Blackhouse G, Bowen JM, Tarride JE, et al. (2009).
Illustrating economic evaluation of diagnostic technologies: comparing Helicobacter
pylori screening strategies in prevention of gastric cancer in Canada. J Am Coll Radiol.
6(5):317–23. http://dx.doi.org/10.1016/j.jacr.2009.01.022 PMID:19394572
27. Lane JA, Murray LJ, Noble S, Egger M, Harvey IM, Donovan JL, et al. (2006). Impact ofHelicobacter pylori eradication on dyspepsia, health resource use, and quality of life in
the Bristol Helicobacter Project: randomised controlled trial. BMJ. 332(7535):199–204.
http://dx.doi.org/10.1136/bmj.38702.662546.55 PMID:16428249
28. Harvey RF, Lane JA, Murray LJ, Harvey IM, Donovan JL, Nair P; Bristol Helicobacter
Project (2004). Randomised controlled trial of effects of Helicobacter pylori infection andits eradication on heartburn and gastro-oesophageal reflux: Bristol Helicobacter Project.
BMJ. 328(7453):1417. http://dx.doi.org/10.1136/bmj.38082.626725.EE PMID:15126313
29. Ford AC, Forman D, Bailey AG, Axon AT, Moayyedi P (2005). A community screening
program for Helicobacter pylori saves money: 10-year follow-up of a randomized
controlled trial. Gastroenterology. 129(6):1910–7.
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30. Harvey RF, Lane JA, Nair P, Egger M, Harvey I, Donovan J, et al. (2010). Clinical trial:
prolonged beneficial effect of Helicobacter pylori eradication on dyspepsia consultations– the Bristol Helicobacter Project. Aliment Pharmacol Ther. 32(3):394–400.
http://dx.doi.org/10.1111/j.1365-2036.2010.04363.x PMID:20491744
31. Gisbert JP, Calvet X, Cosme A, Almela P, Feu F, Bory F, et al.; H. pylori Study Group of
the Asociación Española de Gastroenterología (Spanish Gastroenterology Association)(2012). Long-term follow-up of 1,000 patients cured of Helicobacter pylori infection
following an episode of peptic ulcer bleeding. Am J Gastroenterol. 107(8):1197–204.
http://dx.doi.org/10.1038/ajg.2012.132 PMID:22613904

120

Annex 1. Search strategy for economics of Helicobacter pylori test and treat to prevent
gastric cancer
1. Helicobacter pylori.mp. or Helicobacter pylori/
34 734
2. Gastric Cancer.mp. or Stomach Neoplasms/
78 492
3. Markov Chains/ or Models, Statistical/ or Markov.mp.
84 8304. Economics, Medical/ or Cost-Benefit Analysis/
69 498
5. 3 or 4
150 856
6. 1 and 2 and 5
53

121

Chapter 3.4
The role of biomarkers of gastric cancer risk to target interventions
Javier Torres
Gastric cancer is currently the fifth most common malignancy in the world, behind cancers of
the lung, breast, and colorectum, and with about 1 million new cases in 2012. Gastric cancer
is also the third leading cause of cancer death in both sexes worldwide, with an estimated723 000 deaths in 2012. More than 70% of these deaths occurred in developing countries,
mostly in Asia and Latin America, and this figure is expected to increase, largely due toageing of the populations in low- and middle-income countries. Gastric cancer is one of theleading cancers in many areas of Latin America, particularly in Central America and in the
Andean countries.
1. Gastric cancer and H. pylori infection
The main risk factor for distal gastric cancer is infection with Helicobacter pylori, the firstbacterium recognized as oncogenic [1]. H. pylori infects the gastric mucosa during childhoodand establishes a chronic long-lasting inflammation that, if not treated, remains for decades.
This persistent inflammation of the gastric mucosa will eventually cause gastric cancer inless than 3% of the infected individuals. An improved understanding of the natural history of
the infection will enable the development of tests for an early diagnosis, or even better, theidentification of patients at risk of developing gastric cancer. H. pylori colonizes the gastricmucosa, where it expresses an array of proteins that allow it to establish a persistentinfection. Most of these factors interact with receptors in gastric epithelial cells to signal
different cellular pathways that eventually lead to changes in the expression of genes
involved in inflammation, cellular proliferation, invasion, and metastasis. Inflammation may
also lead to chronic long-lasting exposure to reactive oxygen species and reactive nitrogenspecies, which cause DNA damage, genetic instability, and gene mutations, eventuallyleading to carcinogenesis. Decades of gastric inflammation may also induce epigenetic
changes, such as methylation of genes, that would also lead to carcinogenesis. Virulence
factors such as CagA, VacA, or LPS interact and modulate cellular signalling pathways (cMET, SHIP, SRC, PAR1, NF-κB, COX-2, etc.) to induce a pro-inflammatory response, oralter tight junctions and cell polarity, and finally favour metastasis [2]. A pro-inflammatory
response would result in increased mucosal levels of cytokines such as IL-1 or IL-8, TNF-α,or PGE2 [3, 4].
2. Considerations
All the bacterial or cellular factors described above represent potential biomarkers for risk,
early diagnosis, or prognosis for gastric cancer, but there are important considerations in theselection of candidates. The utility of biomarker tests is optimized when they are applied in
the right context. The association of genetic polymorphisms with gastric cancer risk largely
depends on ethnicity, and thus it should be determined which single-nucleotide
polymorphisms (SNPs) apply to a population before using them as biomarkers. Age is also
important, and most markers for unregulated inflammatory response, such as alteredmicroRNA (miRNA), DNA methylation, or altered glycomics and proteomics, would be more
useful in older adults, when precancerous lesions are more likely (probably after age
40 years). Infection with cagA-positive strains was found to be significantly associated withprecancerous lesions in individuals with type A blood group, but not in those with other ABO
groups [5]. In a patient with family history of gastric cancer, “test and treat” for H. pylori
infection would be advised, even in the absence of biomarkers. Gastric cancer is amultifactorial disease, and a proper combination of markers, including host genetic factors
122

(e.g. polymorphisms in inflammation-associated genes, age), H. pylori virulence factors (e.g.
cag pathogenicity island, cagA and vacA genes), or environmental factors (e.g. diet, salt
intake), may improve their utility to identify patients at risk.
3. The challenge for biomarkers in cancer
After decades of investigation for biomarkers useful in cancer, very few biomarkers havebecome useful in the clinic; the Early Detection Research Network of the United States
National Cancer Institute (http://edrn.nci.nih.gov/) is an organization that promotes andsupports studies for the discovery and validation of cancer biomarkers, and after hundreds ofmillions of dollars have been invested for about 10 years, none of the biomarkers studied
have yet been approved for clinical use [6]. In fact, very few cancer biomarkers already inclinical use have high sensitivity and specificity, and for many of them, whether they really
improve cancer outcome is currently questioned. In the coming decades, the incidence ofgastric cancer in developing countries will increase, largely because of ageing of the
population [7]. It is in these countries where identification of patients at risk and early disease
detection are most needed, but it is also in these countries where resources for health are
limited. Thus, biomarker tests for these regions must be non-invasive, simple, and cheap,
which makes the task of discovery and development even harder [8].
4. Biomarkers for distal gastric cancer: H. pylori
A major difference between gastric cancer and other tumours is that a bacterial infection is
the strongest risk factor for most of the cases, initiating the cascade of events that set up theinitial conditions for other risk factors to further increase the risk of cancer development. The
importance of this is that, hypothetically, by eradicating the infection with antimicrobial
therapy, it would be possible to prevent most of the gastric cancer cases; unfortunately, thisis not that simple. H. pylori infects more than 50% of the world’s population, and indeveloping countries the prevalence is as high as 80% in adults [9]; still, less than 3% of
those infected will ever develop gastric cancer. In addition, it has been argued that early
infection may protect against autoimmune diseases during adulthood, probably by “training”
the immune system [10, 11]. Furthermore, evidence has been presented to show that
eradication of H. pylori increases the risk of oesophageal cancer [12]. Still, H. pylori isestimated to increase the risk of gastric cancer 3–6-fold [13, 14], and detection of theinfection is then a marker of risk. Several studies have found that serological detection of H.
pylori may be improved if combined with the serological detection of virulence factors like
CagA, particularly for pre-neoplastic lesions [14–18]. A meta-analysis concluded thatsearching for CagA in addition to H. pylori infection may confer additional benefit byidentifying patients at greater risk for gastric cancer [19]. However, CagA-positive strains are
so common in Asia that its detection may not help to distinguish patients at increased risk forgastric cancer [20, 21]. Recently, a multiplex assay to detect antibodies to several other H.
pylori proteins has been tested in a high-risk region of China, and showed that assessmentof additional virulence factors may improve the ability to identify patients at risk for gastriccancer [22].
5. Regional gastric cancer mortality rates
The regional gastric cancer mortality rate is a geographical marker for populations at risk
and an important criterion in the selection of populations at greater need of targetedintervention programmes. According to GLOBOCAN 2012 estimates, Asia, eastern Europe,
Central America, and Andean countries in South America are the regions with the highest
mortality rates [23]. Large clinical trials for eradication in populations with high mortality rates
have been performed in China and Colombia [24, 25]; both showed a significant effect inpreventing development of cancer and in regression of pre-neoplastic lesions. Even within
high-risk countries, screening in high-risk groups might be more effective, as shown in astudy in Singapore, where screening limited to Chinese men aged 50–70 years [26] was123highly cost-effective and the endoscopic screening of 199 000 subjects prevented 743
gastric cancer deaths and saved 8234 absolute life-years.
6. Pepsinogens
It is accepted that in the case of intestinal gastric cancer, gastric atrophy represents theearliest pre-neoplastic lesion detectable [27, 28], and histological detection after endoscopy
and biopsy has been used in the identification of such cases. Pepsinogen I (PgI) andpepsinogen II (PgII) are produced by cells from the gastric mucosa, and gastric atrophy
alters the production of pepsinogens, which can be measured in serum [29]. Accordingly,
serological levels of PgI and PgII have been shown to be a reliable marker for atrophy in thegastric mucosa, and the pepsinogen test is currently considered to be a “serologicalendoscopy” [30]. Most studies to date on the utility of the pepsinogen test have been
performed in Asian countries, where evidence shows that it is a useful serological test to
identify patients with gastric atrophy. In a pooled analysis of Japanese studies in a total of
about 300 000 individuals, the pepsinogen test resulted in a sensitivity of 77% and a
specificity of 73% [31] for gastric atrophy, suggesting that the test is reliable as a marker for
the identification of individuals at risk of progression to intestinal gastric cancer. Additional
studies have shown that a PgI/II ratio > 3.0 results in a sensitivity of 93% and a specificity of
88% for the absence of atrophy, and patients with these values might be excluded fromfurther screening studies [32]. The utility of the test might be improved if combined withserology for H. pylori infection. In a follow-up study in 9000 Japanese individuals, those withboth H. pylori positivity and low pepsinogen levels had a risk of developing gastric cancer 6–
8 times that of those negative for both tests. Furthermore, individuals negative for H. pylori
but positive for pepsinogens showed a higher risk than those only H. pylori-positive,
presumably because in advanced atrophy H. pylori can no longer grow, and disappears [33].
The synergistic effect of H. pylori and pepsinogens has been confirmed in longitudinal cohort
studies. A study in 2859 Japanese individuals determined gastric atrophy by the pepsinogentest (PgI ≤ 70 ng/mL and PgI/II ≤ 3.0) in a basal sample and followed up individuals for a
median of 9.3 years. Basal serological atrophy increased the risk of developing gastriccancer (hazard ratio [HR], 3.74; 95% confidence interval [CI], 2.13–6.57), and the riskincreased when both pepsinogens and H. pylori were positive (HR, 11.23; 95% CI, 2.71–
46.51); still, the highest risk was in the group who were positive for pepsinogens but
negative for H. pylori (HR, 14.81; 95% CI, 2.47–88.8) [34]. Another study in 4655
asymptomatic Japanese individuals followed up for 7.7 years reported that in contrast to thegroup who were H. pylori-negative and pepsinogen-negative, patients who were H. pyloripositive and pepsinogen-negative had a hazard ratio of 7.13, but those who were H. pyloripositive and pepsinogen-positive had a hazard ratio of 14.85 to develop gastric cancer
during the follow-up period; the group who were H. pylori-negative and pepsinogen-positive
had a hazard ratio of 61.85 [27]. Similarly, a study in 1501 Chinese individuals, followed up
for 14 years, found that abnormal pepsinogen levels were associated with increased risk ofgastric cancer (relative risk [RR], 4.22; 95% CI, 1.91–9.33), but in individuals with both H.
pylori infection and abnormal pepsinogen levels, risk of developing gastric cancer was evenhigher (RR, 27.46; 95% CI, 3.34–225.4) [35].
Limited studies have evaluated pepsinogen levels in countries outside of Asia. One
performed in Finland screened 22 436 men by PgI level, with a cut-off value of PgI< 25 ng/mL [36]. The study found 2196 individuals with low PgI levels, and endoscopy was
performed in 1344 of them, finding moderate to severe atrophic corpus gastritis in 78%. In
contrast, in 136 men with PgI > 50 ng/mL, only 2.2% presented atrophic gastritis. Among the1344 individuals with low PgI levels, neoplastic lesions were found in 63, and early cancer in
7; these were cured by surgical removal, showing the importance of early detection toprevent death. Pepsinogen levels were also validated as serum biomarkers in a study that
included a subsample of 284 patients from the Eurohepygast cohort [37]. In that study, only
the PgI/II ratio was useful to identify patients with atrophy, and a cut-off value of 5.6 showed124

a sensitivity of 65% and a specificity of 77.9% for H. pylori-related corpus-predominant or
multifocal atrophy. The association of low levels of PgI with gastric cancer rates was studied
in 17 populations (mostly European), and it was found that low PgI levels were associatedwith areas of high rates of gastric cancer [38]; this association was observed in men but not
in women. A study nested in the European Prospective Investigation into Cancer andNutrition evaluated 233 gastric cancer cases diagnosed after enrolment and 910 controls;
atrophic gastritis was considered when basal PgI levels were < 22 ng/mL [39]. PgI levels< 22 ng/mL were found in all gastric cancer patients, with an odds ratio of 3.3, which in thecase of non-cardia gastric cancer increased to an odds ratio of 6.5. In cardia gastric cancer
cases with low PgI levels, the risk increased to an odds ratio of 11.0. A study in Thailand
reported that patients with gastric cancer presented lower PgI/II ratios than patients in thegastritis control group (odds ratio [OR], 2.3; 95% CI, 1.10–4.80) [40]. These studies indicatethat the pepsinogen test accurately detects gastric cancer, due to the fact that most patientsstill present with gastric atrophy [41].
Few studies have been performed in Latin America, and most of them with a small sample
size. In Mexico, a study in 205 patients identified chronic atrophic gastritis by histology in
70% of the cases, and PgI < 25 ng/mL identified those cases with a specificity of 100% but asensitivity of only 6%, whereas PgI/II < 2.5 had a specificity of 96% but a sensitivity of 14%[42]. In that study, serology for CagA resulted in a sensitivity of 83% and a specificity of 41%.
In contrast, a study in Costa Rica, a country with one of the highest mortality rates for gastriccancer, conducted in 501 dyspeptic patients reported that PgI/II < 3.4 resulted in a sensitivityof 91.2% but a positive predictive value as low as 11.2% to identify atrophic body gastritis[43]. The study also suggested that serology for CagA antibodies may improve the efficacy
to detect atrophic gastritis. Differences between these two Latin American studies are thatthe gastric cancer mortality rate in Costa Rica is about 2.6 times that in Mexico, and that in
Mexico the study was performed in asymptomatic subjects, whereas in Costa Rica dyspeptic
patients were included. Still, the contrasting results between the two countries are hard to
explain. In another study, conducted in Mexico in 180 healthy volunteers, atrophy wasmeasured in multiple biopsies from antrum and corpus. The performance of PgI/II ratio
varied according to the cut-off value; with a cut-off value of 6.7, the test showed a sensitivityof 75% and a specificity of 71.2%, whereas a cut-off value of 3.2 resulted in a sensitivity of
25% and a specificity of 95.7% [44]. Thus, more studies are needed in Latin America tobetter establish the performance of the test and to define cut-off values for the population.
The use of the pepsinogen test has some limitations that need to be considered. Since thetest detects atrophic gastritis, it is not effective for screening of diffuse gastric cancer, andperformance would vary depending on the proportion of diffuse gastric cancer in the
population. This is important because in countries with the highest gastric cancer mortality
rates, like Honduras, the proportion of the diffuse type in relation to the intestinal type seems
to be increasing [45]; this tendency has also been observed in Mexico (Fig. 3.4.1) andParaguay (J. Torres, unpublished observations). Also, in regions with low gastric cancer
incidence, which is the case in many countries, the test would have a low positive predictive
value [46].

125Fig. 3.4.1. Trends in proportion (%) of diffuse and intestinal gastric cancer in Mexico (1995–2012).

DiffuseIntestinal

The prevalence of pre-neoplastic lesions would also affect the performance of the test. A
systematic review of the prevalence of intestinal metaplasia in 29 countries on fivecontinents found that prevalence of intestinal metaplasia ranges from 3% in Argentina to
55% in New Zealand [47], i.e. a difference of almost a factor of 20 between the country withthe lowest and the country with the highest prevalence. Autoimmune diseases can also
cause chronic atrophic gastritis, like when anti-gastric parietal cell antibodies (APCA) arepresent. This was addressed in a study in 9684 Germans, where pepsinogens, APCA, andH. pylori antibodies were measured in serum [48]. Atrophic gastritis was diagnosed with a
low PgI/II ratio, and the study showed a significant correlation between low PgI/II and APCA,
a correlation that was even stronger in H. pylori-negative subjects (OR, 11.3) than in H.
pylori-positive patients (OR, 2.6), illustrating that the pepsinogen test may also detect gastricatrophy not associated with H. pylori infection. The Asia-Pacific conference stated withmoderate agreement that “low pepsinogen level and low PgI/II ratio may be useful as amarker to identify populations at high risk for gastric cancer” [49], whereas the European
guidelines for the management of precancerous conditions stated, also with moderateagreement, that “serum pepsinogens levels can predict extensive atrophic gastritis”,
although only 50% of the national societies mentioned that this would be applicable in theircountries [50]. In addition, the pepsinogen test is still too expensive to use in communitybased screening programmes, particularly in countries in Latin America and Asia that
present the highest mortality rates. Still, pepsinogen tests currently represent the mostreliable and practical test to screen populations and identify those who deserve close followup by means of invasive endoscopic methods.
7. Gastrin-17
Serum gastrin-17 (G-17) is produced by G cells in the antrum, and circulating gastrin has
been suggested as a serological marker to distinguish antral atrophic gastritis from corpus
atrophic gastritis [29, 51]. In particular, patients with atrophic antral gastritis present with lowlevels of circulating G-17. However, the relationship between G-17 and gastric physiology iscomplicated; H. pylori may induce a pan-gastritis, and when atrophy affects the body, it
126

usually also affects the antrum, so that in H. pylori-positive patients, a low G-17 level isassociated with atrophy in both antrum and corpus [29]. The G-17 level increases
substantially in gastric cancer and does not help to distinguish early from advanced cancer[52]. Gastrin circulates as several bioactive peptides, and all need to be measured for aproper diagnosis; however, available antibodies fail to efficiently identify all forms. Other
important technical drawbacks are that G-17 has a very short half-life and that available
commercial kits vary extensively in their performance, with more than half displaying
inaccurate performance [53]. Finally, it should be considered that abnormal gastrin levels
occur also in other gastrinomas, such as Zollinger–Ellison syndrome. Considering the above
and the fact that adding G-17 to the pepsinogen and H. pylori tests does not significantly
improve efficacy, G-17 would not be recommended for screening programmes.
8. Current national programmes in Asia
Japan and the Republic of Korea, the Asian countries with the highest gastric cancer
mortality rates, have national or regional screening programmes to identify early gastriccancer cases. Japan uses barium X-ray as a government-sponsored nationwide programmein asymptomatic individuals older than 40 years. In the Republic of Korea, the National
Cancer Screening Program recommends biennial screening for individuals older than
40 years, with direct upper-gastrointestinal series or endoscopy. In China, there is nonationwide screening programme, and early detection relies on opportunistic screening;
also, barium-meal and serum pepsinogen tests are not commonly used because of cost andavailability [54].
9. Novel approaches
There are several recent studies searching for markers that may distinguish normal
individuals from those with pre-neoplastic lesions, which take advantage of what is being
learned about the natural history of gastric cancer. Although they are still far from clinical use
or from being recommended in population screening programmes, such markers should beconsidered for studies in large groups in regions with high gastric cancer mortality rates,
particularly in Asia and Latin America, to better elucidate their potential use in a particular
population.
The gastric inflammation caused by H. pylori induces the release of several pro-inflammatory
mediators, among which the most studied include IL-1β, IL-8, TNF-α, IL-10, and IL-6 [3, 4]. A
study in 226 consecutive patients, 150 of whom were receiving acid inhibitory treatment for
reflux disease, found that serum IL-8, IL-6, and IL-1β levels were significantly higher inpatients with atrophic gastritis [55]. The authors of that study constructed an index using theIL-8-to-pepsinogen ratio and reported that this index was significantly better than serum
gastrin or pepsinogen levels alone at correctly classifying atrophic gastritis cases. A recent
study also showed that high levels of IL-8 were significantly associated with risk of gastriccancer (OR, 2.1), although increased levels of IL-1β, IL-2, IL-4, IL-6, IL-10, TNF-α, or IFN-γ
were not [56]. Many studies have looked for polymorphisms in inflammation-related genes,
among which IL-1β and its antagonist IL-1RN have been extensively studied, although withconflicting results. A meta-analysis found a consistent association of the IL-1β-511 SNP withgastric cancer in Caucasians but not Asians [57], whereas another meta-analysis reported
that this SNP was associated with the intestinal but not the diffuse type of gastric cancer[58]. Still, another recent meta-analysis failed to identify any significant correlation of the
SNPs in both IL-1β and IL-1RN with gastric cancer [59]. Studies in a Latin American
population have also found a lack of association of IL-1β with gastric cancer, althoughgenotypes TNF-β-252G/G and HSP70-1C/G were found as risk markers for gastric cancer[60]. Polymorphism in IL-8 has also been reported to be associated with gastric cancer risk,
and an SNP in the promoter -251A was reported as associated with risk of intestinal gastriccancer, and the -251T SNP as associated with risk of diffuse gastric cancer [61]. A recent
127meta-analysis concluded that the IL-8-251 AA genotype is associated with risk of gastriccancer, particularly of the intestinal type, in Asian populations but not in other groups [62]. IL10 as a modulator of inflammatory mediators plays a major role in inflammation-driven
gastric cancer, and SNPs in the gene have been studied in gastric cancer. In fact, metaanalyses have found that IL-10-592 AA [63] and IL-10-819 TT [64] are associated with areduced risk of gastric cancer in Asian populations.
The study of the role of miRNAs in the regulation of gene expression is an expanding field,
and cancer is not the exception. In cancer development, miRNAs may function as
oncogenes or as tumour suppressor genes since they regulate cell proliferation, apoptosis,
differentiation, and even inflammation, all important in the genesis of gastric cancer. The
miRNAs can help identify individuals at risk, as exemplified in Japanese [65] and Chinese[66] populations, where the rs2910164 (G > C) SNP in miR-146a was associated withsusceptibility to gastric cancer. SNPs in miR-196a-2 [67], miR-27a [68], and miR-378 [69]have also been found to be associated with susceptibility to gastric cancer in Chinese
populations. The analysis of circulating miRNA offers a promising non-invasive alternative totest for susceptibility to gastric cancer, although it should be considered that a single
polymorphism may be associated with risk for different tumours and candidates should be
evaluated for acceptable specificity and sensitivity. Clearly, much has been learned about
genetic polymorphisms as risk factors for gastric cancer in Asia, particularly Japan and
China, but an effort should be made to study this in other human groups with high gastriccancer mortality rates, including other countries in Asia and Latin America. Another factor toconsider is that when analysing the utility of gene alleles as biomarkers for gastric cancer
risk in different human groups, it should be noted that allele frequencies vary widely acrosspopulations, which may affect the statistical power of allele differences to detect an effect onrisk [70].
The human intestinal microbiota has been shown to play a major role in health and disease,and its study has been suggested as a potentially useful biomarker to identify individuals at
risk of diseases like diabetes, obesity, inflammatory bowel disease, or even colon cancer[71]. The study of microbiota in the stomach may also show some utility as a marker of risk
or prognosis for gastric cancer. It has also been suggested that when H. pylori infection
leads to atrophy and hypochlorhydria, the gastric environment becomes more permissive tocolonization with other bacteria, which in turn may increase the inflammatory and immune
response of the gastric mucosa, and modulate mucosal damage and the development of
pre-neoplastic lesions. Initial attempts to characterize microbiota in gastric cancer samples
have reported no significant differences with dyspeptic controls [72]. Given the diversity of
microbiota structure across individuals and across populations, regional studies are needed
to gain insight into its diversity in each population.
Several studies have been performed on the identification of candidate proteomic andglycomic biomarkers circulating in plasma, which report molecules able to distinguish gastriccancer or pre-neoplastic lesions from gastritis [73–76], and these constitute potential
biomarkers for use in the screening of individuals at risk for gastric cancer.
10. Other considerations
It should be kept in mind that gastric cancer is a multifactorial disease and that a proper
combination of markers may improve their utility to identify patients at risk. The utility of abiomarker test is optimized when it is applied in the right context. The association of genetic
polymorphisms with gastric cancer risk largely depends on ethnicity, and thus it should bedetermined which SNPs apply to a population before using them as biomarkers. Age is also
important, and most markers for unregulated inflammatory response, altered miRNA, DNA
methylation, altered glycomics or proteomics, would be more useful in adult ages when
precancerous lesions are more likely (e.g. after age 40 years). Blood group background may
128also influence outcome; infection with cagA-positive strains was found to be significantly
associated with precancerous lesions in individuals with type A blood group, but not in thosewith other ABO groups [5]. At present none of the suggested biomarkers for gastric cancer
has been approved for clinical use, and they are even farther from being ready for use forlarge-scale screening. However, in a patient with family history of gastric cancer, “test andtreat” for H. pylori infection would be advised, even in the absence of other biomarkers.
When planning for a community screening programme, important points to consider are thatthe test should be validated for accuracy and high predictive value in the population being
studied, and it should be non-invasive, simple, cheap, and accessible. The serological testfor H. pylori is widely available and inexpensive, and serological tests for gastric atrophy arealso available, and although not yet inexpensive, they offer the opportunity to test both in thesame minimally invasive sample.
11. Suggested strategies for Latin America
In Latin America, no population strategies have been suggested so far, despite the fact thatthe region contains areas with gastric cancer mortality rates among the highest in the world.
A first approach should consider that the pepsinogen test has not proven as efficient in Latin
America as in Asia to detect atrophy. Also important is the reported increasing trend indifferent countries of the diffuse type of gastric cancer, for which no precancerous lesions
have been described yet. Still, an initial selection by country and by district or county might
help better target screening programmes. Latin America is a region with limited resources for
public health, and an initial screening should be simple and cheap. Probably, after initial
selection of districts, screening could be performed in adults older than 40 years for H. pylori
using either serology or the urea breath test, and then eradication treatment could be given,as suggested in Fig. 3.4.2.
Fig. 3.4.2. Suggested minimal screening in the Latin American region. GC, gastric cancer; Hp,
Helicobacter pylori; UBT, urea breath test; tx, therapy; y, year.

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Chapter 3.5
Current and ongoing research projects related to gastric cancer
prevention: perspective of the United States National Cancer
Institute
Christian C. Abnet
Gastric cancer rates make it the third leading cause of cancer death worldwide, and new
diagnoses may top 1 million per year in the near future. In the USA, as in many economicallydeveloped countries, total gastric cancer incidence rates continue a steady decline, with aconcomitant decrease in gastric cancer mortality. In contrast to this overall encouraging
trend, severable notable concerns remain. First, the incidence and mortality rates for gastriccancer have declined in all racial/ethnic groups, but Hispanic and non-White United States
residents have rates almost twice those seen in non-Hispanic Whites. Second, the incidence
rate trends for cardia gastric cancer may not have declined in parallel with those of noncardia gastric cancer, but the difficulty of separating cardia and oesophageal
adenocarcinoma makes this difficult to assess. Third, the declines in total gastric cancer may
not be apparent in all age groups [1]. A significant increase in non-cardia gastric cancer
incidence rates at certain subsites has been detected in United States Whites aged 25–
39 years [2]. These findings demonstrate some of the remaining concerns about gastriccancer in the USA. But the United States National Cancer Institute (NCI) also has acommitment to advance cancer research globally, where gastric cancer remains a major
cause of cancer death, and this is reflected in the recent formation of the NCI Center for
Global Health (http://www.cancer.gov/aboutnci/globalhealth). The NCI financial commitment
to gastric cancer research peaked in fiscal year 2009 at US$ 15.4 million(http://www.cancer.gov/researchandfunding/snapshots/stomach).
The NCI Intramural Research Program conducts many primary research projects ininternational settings (http://www.cancer.gov/researchandfunding/intramural), and this has
been particularly true for gastric cancer. The intramural programme includes basic scientists,
population scientists, clinical scientists, and translational scientists working ininterdisciplinary teams. The programme conducts a wide range of gastric cancer studies,including studies of etiology (e.g. [3, 4]) and an expanding portfolio examining the role of
Epstein–Barr virus [5, 6], but this chapter summarizes the recent activities of the NCI
intramural programme that examine gastric cancer with a particular focus on prevention.
1. Extended follow-up of gastric cancer prevention trials
In 1985, NCI and the Cancer Institute, Chinese Academy of Medical Sciences initiated two
companion randomized placebo-controlled intervention trials to test whether
supplementation with vitamins and minerals could be used to prevent upper gastrointestinal
cancer in a nutrient-deficient high-cancer-incidence population in Henan Province, China [7].
The larger trial (General Population Trial) included nearly 30 000 apparently healthy subjects
aged 40–69 years and randomized them to one of four vitamin and mineral combinations
using a partial factorial design such that one half of the subjects received each of the fourinterventions. The smaller trial (Dysplasia Trial) enrolled 3318 subjects who had previously
been diagnosed with oesophageal dysplasia via balloon cytology. This method has relatively
low sensitivity and low specificity [8, 9] but will result in a population group with higher-thanaverage cancer risk. The Dysplasia Trial used a non-factorial design to test the use acommercial multivitamin plus β-carotene. The intervention portion of both trials concluded in
1991, and the results were published at that time [10, 11]. All subjects remain under followup to this day, and the cohort has been used extensively to address numerous etiological136

hypotheses. Recently, the trial was re-analysed after 10 years (General Population Trial) or
20 years (Dysplasia Trial) of additional follow-up, to assess the durability of the intervention
effects and to test for any late occurring effects. At the end of intervention, the General
Population Trial showed that a combination of selenium, α-tocopherol, and β-carotene
significantly reduced the incidence of gastric cancer by 21% and total mortality by 9%. Reanalysis of the data after continued follow-up showed that this effect was highly durable andthat even 10 years after supplementation ended, subjects were at 11% lower risk ofdeveloping gastric cancer [12]. Observational studies examining serum concentrations at
study baseline suggest that selenium is the most likely agent to confer this benefit, sincehigher baseline selenium was associated with lower risk of gastric cancer [13], whereas βcarotene showed no association [14] and higher α-tocopherol serum concentrations wereassociated with elevated risk [15]. The Dysplasia Trial showed that multivitamins had noeffect on cancer risk either at the end of the trial [11] or during extended follow-up [16].
The Peking University School of Oncology and NCI conducted a multifactorial intervention
trial in 3365 subjects from Shandong Province, a region with extraordinarily high rates ofgastric precancerous lesions and gastric cancer. The trial tested one-time Helicobacter pylori
treatment and long-term use of vitamin or garlic supplements. The eradication therapy
showed statistically significant decreases in the combined prevalence of severe chronic
atrophic gastritis, intestinal metaplasia, dysplasia, and gastric cancer 5 years and 9 years
after treatment, but there was no effect of the nutritional interventions [17]. Subsequent
analysis after additional follow-up showed a significant reduction of gastric cancer incidencewith H. pylori treatment and now revealed that the 7.3 years of treatment with vitamin C,
vitamin E, and selenium significantly reduced mortality due to gastric and oesophageal
cancer combined [18], a secondary trial end-point.
Beyond the important findings of the Shandong Trial on H. pylori eradication, these trials
suggest that in some populations, likely those with deficiencies, nutritional interventions may
be an effective method of reducing gastric cancer incidence. Fortification programmes fornumerous vitamins and minerals are used in many parts of the world. Demonstration
projects to test population-level fortification to prevent gastric cancer would provide further
insight and may lead to important reductions in the incidence of this cancer.
2. H. pylori serology and cancer risk
Several cohort studies have been pursued to examine the strength of the association
between H. pylori serology and gastric cancer in different settings. The results suggest that
positive H. pylori serology carries greater apparent relative risk in the Finnish population,
which has lower background infection rates [19], than in China, where the large majority ofthe population tests positive for evidence of past or current H. pylori infection [20]. Recently,
some of the populations have been retested to assess whether use of a serological test thatcovers a broad array of antigens [21] can provide additional risk information.
Several areas of the world that have high rates of oesophageal squamous cell carcinoma(ESCC) also have high rates of gastric cardia adenocarcinoma. The risk factors for gastriccardia cancer in these areas tend to show some overlap with risk factors for ESCC and to be
distinct from the apparently reflux-induced gastric cardia cancers in populations that havehigher rates of oesophageal carcinoma, such as those in Europe, North America, andAustralia. NCI has conducted H. pylori serology studies in Linxian, China, where gastriccardia cancer predominates 5:1 over non-cardia gastric cancer [20], and in the Shanghai
Women’s Health Study [22], where, as is more common in China and elsewhere, non-cardia
cancer predominates 9:1 over cardia gastric cancer. In these studies, it was found that H.
pylori seropositivity conveys similarly elevated risks for cardia and non-cardia gastric cancer[20]. This is quite distinct from the situation in Europe, North America, and Australia, where
H. pylori seropositivity may be associated with lower risk of cardia cancer [19].
137To fully assess the role of H. pylori in human health, NCI has also extended some of theseserology studies beyond its original focus on gastric cancer. With the Linxian General
Population Nutrition Intervention Trial cohort, the association of H. pylori seropositivity with
ESCC was examined, and no association was observed [20]. And a similar null result wasobserved for ESCC in the Finnish Alpha-Tocopherol, Beta-Carotene Cancer Prevention
Study cohort [23]. Other studies from NCI have examined the association of H. pylori
seropositivity with pancreatic cancer, which showed mixed results [24, 25], and mostrecently with biliary tract cancer, which showed a substantially increased risk (unpublisheddata).
3. Other seromarkers for gastric cancer risk
In populations with high incidence rates, endoscopic screening programmes have thepotential to reduce disease-specific gastric cancer mortality, but few health systems have thewherewithal to support endoscopic screening of all at-risk individuals. Therefore, serologicalmarkers have been of interest to allow for lower-cost triage of subjects who may be at thehighest risk for gastric cancer. A large number of studies have tested the association
between serum pepsinogen concentrations and gastric cancer risk in both cross-sectional
and prospective studies, although there have been no randomized controlled trials of serum
pepsinogens as a screening method that tested whether this can reduce mortality due togastric cancer. NCI has examined serum pepsinogens in three prospective studies (theNutritional Intervention Trial, the Shanghai Women’s Health Study cohort, and the AlphaTocopherol, Beta-Carotene Cancer Prevention Study cohort) and showed strong
associations, similar to other groups. At least 13 groups have examined the association withgastric cardia cancer [26] and many dozens for non-cardia cancer [27], although many ofthese studies have not been prospective, which may be less informative with regard to theutility as an early detection method. It appears that serum pepsinogen I (PgI) concentration
may be of greatest use in the few years before cancer diagnosis, but that serum pepsinogen
II (PgII) concentration and PgI/II ratio may have independent value over a longer period [22,28]. Furthermore, many previous studies have used dichotomization of pepsinogenconcentrations as risk markers, but this may substantially reduce the predictive power ofthese markers, given the apparent linear association between the PgI/II ratio and gastriccancer risk [28].
If additional markers with independent predictive powers can be identified, the predictive
power of these tests may be improved. Recently, NCI tested the association between uppergastrointestinal cancer risks and serum concentrations of ghrelin, a gastric hormone that
may stimulate gastric acid, regulate energy balance, and control appetite. The study showedstrong associations that are independent of pepsinogen concentrations for multiple uppergastrointestinal malignancies [29, 30]. Replication in additional studies will be crucial to test
whether serum ghrelin should be added to future trials of gastric cancer screening
methodologies.
4. Gastric cancer genetics
Hundreds of studies have examined whether common genetic variants alter gastric cancer
risk. But the utility of hypothesis-driven testing of single-nucleotide polymorphisms has beencalled into question, and many reported associations have not been confirmed insubsequent studies [31]. Genome-wide association studies (GWAS) have dramatically
improved the problem of non-replication. NCI is currently pursuing a comprehensive set of
GWAS studies of upper gastrointestinal cancers in multiple ethnic groups. The firstpublication examined the top hits for ESCC and gastric cancer in a study of ethnic Chinese
subject [32]. That study found that for populations in central China, a single genomic locus at
10q22 had the strongest association with risks for both ESCC and gastric cardia cancer, but
138

no association with non-cardia cancer. Several subsequent studies have confirmed thisfinding. Despite a relatively high odds ratio of 1.57 per allele for gastric cardia cancer in thatstudy, common variants are unlikely to be used as a risk-stratifying exposure. The utility ofcommon genetic variants for individual risk prediction has been explored in depth, and evenin the situation where a large number of variants have been confirmed, these are unlikely to
be useful for this purpose [33, 34]. The 10q22 genomic region harbours the PLCE1 gene,which has been linked to altered risk of cancer at several sites and with different carcinogens
in animal models. It remains possible that these associations will lead to additional
etiological insights. A deeper examination of the data for cardia and non-cardia gastriccancer is in process with NCI collaborators from China and other parts of East Asia. NCI isalso pursuing a GWAS for gastric cancer in subjects of European/Caucasian descent, andresults will be published in the near future.
NCI laboratories have also explored other aspects of gastric cancer genetics, including adetailed examination of gene expression differences between cardia and non-cardia tumours[35]. In addition, microRNAs show promise as early detection markers or therapeutic targets,and some early work in characterizing gastric cancer miRNAs has been carried out at NCI[36].
5. Conclusion
This chapter has summarized current and ongoing research projects related to gastriccancer prevention in the NCI intramural portfolio. Promising results from nutritional
intervention trials suggest that nutritional fortifications should be further explored for theirpotential to reduce the incidence of gastric cancer in addition to trials of H. pylori eradication.
Gastric cancer screening may be appropriate in some populations, and work with serum
pepsinogens and ghrelin suggests that serological markers could play a role in risk
stratification as an adjunct to an endoscopic screening programme, but at present thisstrategy remains unproven through cancer control trials. Ongoing work at NCI in genetics
has revealed interesting findings with regard to gastric cancer susceptibility, but thetranslation potential of this works remains to be developed. NCI intramural programme
investigators continue work in gastric cancer prevention research and aim to makesubstantial contributions in reducing the suffering and death due to this all-too-common
disease.

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Chapter 4.1
Current gastric cancer prevention strategies in Linqu County, ahigh-risk area in Shandong Province, China
Wei-Cheng You
Nearly 1 million new gastric cancer cases occur annually worldwide, 40% of them in China[1–3]. The prognosis of gastric cancer varies markedly by the stage of cancer; the 5-year
relative survival rate can reach 90% for cancers detected in stage I but is less than 5% for
those detected in stage IV [4]. Therefore, efforts have been made in China to detect gastriccancer in the early stages and develop primary prevention strategies.
There is a considerable geographical variation in the incidence of gastric cancer in China,
with higher incidence rates in the northern and central regions of the country. Linqu County,
in Shandong Province in north-eastern China, is a rural area with one of the highest gastriccancer incidence rates. The age-adjusted (world standard) mortality rate per 100 000 per
year for gastric cancer in Linqu County was 70 for men and 25 for women in 1973–1975,
accounting for 42% of the total cancer deaths in that region [5]. Since 1983, epidemiologicalstudies of early detection of gastric cancer have identified risk factors including Helicobacter
pylori infection, H. pylori virulence factors, genetic susceptibility, dietary factors, andinteractions among risk factors associated with gastric cancer and precancerous gastriclesions. Based on the accumulated evidence, three intervention trials have been conductedin the high-risk population in Linqu County since 1995.
1. Early detection of gastric cancer in Linqu County, a high-risk area for gastriccancer
In 1989–1990, endoscopic mass screening was conducted among 3400 adults aged 35–
64 years in Linqu County. A total of 13 gastric cancers were detected in this screening(detection prevalence rate, 0.38%), of which 64% were in stage I or II [6]. To assess whether
endoscopic screening could be made more cost-effective by identifying subjects at highest
risk, a study evaluated using the ratio of pepsinogen I to pepsinogen II levels (PgI/II) in
serum as a risk marker, but it was found to not be sensitive or specific enough [7]. From2008 to 2011, a further study examined the impact of PgI/II compared with direct endoscopy
in the early detection of gastric cancer in 2290 residents aged 40–69 years in Linqu County,
and found that endoscopy had a higher detection rate than PgI/II for gastric cancer (oddsratio [OR], 2.83; 95% confidence interval [CI], 1.34–5.98) and for early gastric cancer/highgrade intraepithelial neoplasia (OR, 2.12; 95% CI, 1.12–4.02). The sensitivity and specificityof PgI/II for detection of gastric cancer were 76.5% and 41.9%, respectively [8].
To identify more specific and sensitive biomarkers for gastric cancer detection, a humangastric carcinoma-associated antigen (MG7-Ag)-specific monoclonal antibody wasdeveloped [9]. A total of 2710 participants aged 35–64 years received an endoscopic
examination. Serum samples were collected to detect MG7-Ag by serum-based immunopolymerase chain reaction (immuno-PCR) assay. Among 2710 participants, 148 (5.46%)
were determined to be MG7-Ag-positive. The sensitivity of the MG7-Ag immuno-PCR assay
for the detection of gastric cancer was 77.5% (31 of 40 gastric cancer cases); the specificity
was 95.62% (2553 of 2670 non-gastric cancer subjects), and the accuracy was 73.12%. A
total of 24 gastric cancer cases were in stage I or II, of which 17 (70.8%) were MG7-Agpositive [10].

143Since the above-mentioned studies revealed that direct endoscopy is more effective than the
PgI/II ratio scheme in detection of gastric cancer, 3018 residents of Linqu County aged 40–
69 years were screened in 2013, and 38 (1.26%) cases of gastric cancer were detected.
Among those gastric cancer cases, 78.95% were in early stages. Since 2008, a nationwide
oesophageal cancer and gastric cancer screening programme by endoscopy has been
implemented, supported by the Chinese Ministry of Health. A total of 110 counties in 26
provinces are enrolled in this project so far. In 2013, a total of 189 329 residents aged 40–
69 years were screened by endoscopy, and 3040 (1.61%) oesophageal and gastric cancers
were detected, of which 2201 (72.40%) of gastric cancer cases were in early stages.
2. Randomized controlled intervention trials to prevent gastric cancer by eradicationof H. pylori in Linqu County, Shandong Province
Half of the world’s population is infected with H. pylori. Accumulated evidence fromepidemiological and experimental studies during the past three decades strongly suggeststhat H. pylori infection causes chronic inflammation of gastric mucosa and increases the riskof gastric cancer [11, 12].
A major risk factor for gastric cancer and its precursors in Linqu County is thought to be H.
pylori infection; 72% of adults (68% of men and 75% of women) and 50–85% of children
aged 3–12 years are infected with H. pylori [13, 14]. The prevalence of H. pylori infection isnearly 3-fold higher among children in Linqu County than among children in Cangshan
County (also in Shandong Province), a low-risk area for gastric cancer.
In an endoscopic survey among 3400 adults in Linqu County, 33% had intestinal metaplasia
and 20% had dysplasia [6]. The prevalence of H. pylori positivity varied markedly byhistological status; the infection rate was 55%, 60%, 87%, and 78%, respectively, for thosewith superficial gastritis, mild chronic atrophic gastritis (CAG), severe CAG, and moreadvanced lesions. The odds ratio for each of the advanced lesions remained significantly
higher after adjusting for sex, age, and cigarette smoking. The subjects with different gastriclesions were subsequently observed for 5 years, and the risk of progression to dysplasia andgastric cancer was 80% higher among subjects with H. pylori infection [15]. The prevalencepatterns and longitudinal outcomes indicated that H. pylori infection primarily enhanced thetransition from superficial gastritis to mild and then to severe CAG, consistent with animportant role of H. pylori infection during the early stages of gastric carcinogenesis.
The effects of treatment of H. pylori infection on gastric cancer prevention and thehistological changes of precancerous gastric lesions were studied in Linqu County. In late1995, a total of 3411 subjects were randomized in a 2 × 2 × 2 factorial design according totheir H. pylori status and received eradication therapy, vitamins plus minerals, or garlicsupplements, or their placebos. After the treatment, repeated endoscopies were conducted
in 1999 and 2003, and clinical follow-up continued until 2010. The trial yielded a statisticallysignificant 40% decrease in the prevalence of severe CAG, intestinal metaplasia, anddysplasia as well as favourable effects on gastric cancer prevention. In total, 19 of 1130
subjects in the active H. pylori treatment arm were diagnosed with gastric cancer in 2003,
compared with 27 of 1128 subjects in the placebo arm (OR, 0.60; 95% CI, 0.47–0.75) [16].
At the 15-year follow-up of this cohort, 34 gastric cancer cases had accrued in the treatmentgroup compared with 52 in the placebo group, supporting that H. pylori eradication can
reduce gastric cancer incidence (OR, 0.61; 95% CI, 0.39–0.96) [17].
From 2002 to 2006, another factorial-designed, randomized, and placebo-controlled trial was
conducted in Linqu County to evaluate the effect of a selective COX-2 inhibitor (celecoxib),
alone or combined with anti-H. pylori treatment, on the progression of precancerous gastriclesions. Of the 1024 participants aged 35–64 years who received the initial anti-H. pylori
treatment or placebo, 919 completed the 24-month treatment with celecoxib or placebo. The
144

H. pylori eradication rate was 78.1%. Eight gastric cancer cases were diagnosed during thetrial, and no significant difference in gastric cancer incidence was found between eachtreatment group and the placebo group. However, the proportion of regression of
precancerous gastric lesions was significantly higher in the anti-H. pylori group than in theplacebo group (59.3% vs 41.2%; OR, 2.19; 95% CI, 1.32–3.64) and was higher in thecelecoxib group than in the placebo group (52.8% vs 41.2%; OR, 1.72; 95% CI, 1.07–2.76)[18].
Although these intervention trials support that eradication of H. pylori can reduce theincidence of gastric cancer, the sample sizes in the trials were relatively small and thus theresults are unconvincing for community-based eradication. Based on a series of
epidemiological studies over the past 30 years in Linqu County, a large population-based
intervention trial with nearly 200 000 residents was launched in 2011 in this high-risk area for
gastric cancer. The study is a collaboration between Peking University Cancer Hospital &Institute and the International Digestive Cancer Alliance/Technical University of Munich,Germany. The purpose of this study is to provide valid evidence whether gastric cancer canbe prevented by the eradication of H. pylori in a population at high risk, so as to inform
implementation of gastric cancer prevention in more areas with high risk of gastric cancer
nationwide.
So far, this large intervention trial is proceeding well. The results of this study will haveworldwide public health implications, especially for countries with a high incidence of gastriccancer. This trial is also expected to provide a great opportunity to evaluate the influence ofH. pylori eradication on the incidence of gastro-oesophageal junction cancer. In addition, thistrial will generate a biorepository for biomarker identification and molecular biological studies
in the intermediate assessment of the impact of the intervention trial.
Because of the evidence from the two intervention trials in Linqu County and another trial in
Changle, a consensus was generated by a small group of influential physicians andscientists in a Summit Workshop on Frontiers in Cancer Chemoprevention organized by the
Chinese Academy of Science and held 17–18 October 2013. The eradication of H. pylori inthe adult population of three or four counties with a high risk of gastric cancer in China is apriority in gastric cancer prevention and is highly recommended by this group. The costs ofthis examination of H. pylori infection and anti-H. pylori therapy in the selected population
should be covered by the insurance of the Chinese government.
3. Conclusion
Evidence derived from studies during the past 30 years strongly supports H. pylori infection
as a risk factor for gastric cancer, one of the leading causes of cancer death worldwide.
Understanding how and when to undertake eradication of H. pylori for gastric cancer
prevention, particularly in H. pylori prevalent areas and in populations at high risk for gastriccancer worldwide, is an important health priority that is currently being investigated in China.

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10. Zhang L, Ren J, Pan K, Ma J, Li J, Shen L, et al. (2010). Detection of gastric carcinomaassociated MG7-Ag by serum immuno-PCR assay in a high-risk Chinese population,with implication for screening. Int J Cancer. 126(2):469–73.
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(2001). Helicobacter pylori infection and the development of gastric cancer. N Engl J
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Chapter 4.2
Multicentre randomized study of Helicobacter pylori eradicationand pepsinogen testing for prevention of gastric cancer mortality(Gastric cancer prevention study by predicting atrophic gastritis;
GISTAR)
Mārcis Leja, Jin Young Park, Martyn Plummer, and Rolando Herrero
Gastric cancer is an important global public health issue in eastern European regions, where
the burden of the disease is substantial. The methods used for gastric cancer screening in
Asia (Republic of Korea and Japan), including photofluorography (barium swallow) andupper endoscopy, are not suitable for organized cancer screening programmes outside East
Asia because of the comparatively lower burden of the disease, cost issues, andacceptance.
Considering the incidence of gastric cancer in parts of the world other than East Asia (e.g.
eastern Europe, South America) and the generally delayed diagnosis (with the exception of
the Republic of Korea and Japan), non-invasive screening for gastric cancer or premalignant
lesions that precede cancer development would be the approach of choice to decrease theburden.
There is sufficient epidemiological and experimental evidence that supports a causal link
between Helicobacter pylori and gastric cancer. A population-based screen-and-treat
strategy for H. pylori, the microorganism directly related to gastric cancer in high-risk areas,
has been recommended in the guidelines in Asia [1] and Europe [2]. Two recent metaanalyses have suggested the cost–effectiveness of such an approach [3, 4].
However, to date no country with high gastric cancer incidence has included mass
eradication of H. pylori in the setting of an organized screening programme; although H.
pylori eradication started to be reimbursed in Japan from February 2013, it is not yet a partof the organized screening programme. There is still limited evidence from clinical trials toprove whether H. pylori eradication with antimicrobial therapy is the approach of choice inentire infected populations or only in selected groups to reduce the risk of gastric cancer,
and whether eradication at advanced stages of atrophy is effective among these patients. In
addition, the potential risks of wide antibiotic use have been studied less thoroughly in thesestudies.
During the past decades, substantial work either in Asia or Europe has been applied to study
serological markers for identification of premalignant lesions in the stomach, in particularatrophy and intestinal metaplasia. Pepsinogens, the pro-enzymes of pepsin, are the mostextensively studied biomarkers. Acceptable performance of pepsinogen tests to detect
atrophy has been reported: sensitivity ranging from 66.7% to 84.6% and specificity ranging
from 73.5% to 87.1% [5–8]. At the same time, substantially lower sensitivity for gastriccancer detection (36.8–62.3%) has been reported when the same cut-off values are used
[9–11]. This would potentially result in missing about half of gastric cancer cases in a
population-based screening setting.
Pepsinogen testing for the identification of subpopulations at increased risk for gastriccancer development has been recommended by the guidelines in Asia [1] and Europe [2,12]; however, this method has not been accepted for organized screening in any country.

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In recent years, there has been a growing interest in developing new biomarkers withpotential application in gastric cancer screening. These efforts include, but are not limited to,proteomic and microRNA marker panels.
In addition, some less-traditional applications for gastric cancer have been suggested
recently. Autoantibodies against tumour-associated antigens have been identified in several
cancer types [13, 14], including gastric cancer. A 45-autoantibody signature was found to
discriminate gastric cancer patients from healthy controls with 59% sensitivity and 90%
specificity [15].
Volatile components detected either by gas chromatography coupled with mass
spectroscopy or with nanosensor technology have also been studied in gastric cancer; arecent pilot study suggested the possibility of using a highly sensitive, cross-reactive,
nanomaterial-based gas sensor to identify and separate volatile marker patterns between
gastric cancer patients and those with benign gastric conditions with 89% sensitivity, 90%
specificity, and 90% accuracy [16].
Yet, there is insufficient evidence available about how effective these different tests are as
gastric cancer prevention strategies in organized cancer screening settings.
It is therefore proposed to conduct a multicentre randomized trial in Latvia, Belarus, and theRussian Federation, areas with a high burden of the disease, with the main objective of
evaluating whether H. pylori screening followed by eradication in participants with positive
results and endoscopy of those with serological evidence of atrophic gastritis can reduce
gastric cancer mortality. The proposed trial will also investigate retrospectively whether
biomarkers of chronic atrophic gastritis can select groups of subjects who require treatment
to achieve comparable gastric cancer reduction. Ultimately, this study will have the potential
to find effective prevention strategies through identifying appropriate target groups that could
derive the most benefits from the treatment.
1. Key hypotheses
Hypothesis 1
H. pylori eradication in subjects positive for the infection with endoscopic follow-up of thosewith evidence of atrophic gastritis in the middle-aged population group in high-risk areas
prevents gastric cancer mortality.
Hypothesis 2
H. pylori eradication is effective to prevent gastric cancer mortality even after thedevelopment of gastric mucosal atrophy.
Hypothesis 3
Certain subgroups (e.g. individuals with atrophy determined by pepsinogen testing, cagApositive individuals) can derive more benefit from H. pylori eradication, and therefore could
be targeted if general population eradication is not feasible.
Hypothesis 4
Combination of biomarker screening (e.g. pepsinogen testing, volatile marker testing) andupper endoscopy is an appropriate strategy in high-cancer-incidence areas to prevent
cancer-related mortality.
2. Objectives
The aim of this study is to search for new intervention strategies to decrease mortality fromgastric cancer in high-risk areas, either by testing in screening settings already established148

methods or by searching for new biomarkers with potential application in gastric cancer
screening.
The primary objective of the study is to determine whether H. pylori screening followed byeradication in positive subjects and endoscopic follow-up of those with serological evidenceof atrophic gastritis reduces mortality from gastric cancer in a high-risk population among
subjects aged 40–64 years.
The secondary objectives are:
1. To determine retrospectively whether biomarkers of chronic atrophic gastritis or otherrelated conditions can select the group of subjects who require treatment to achieve
gastric cancer reduction comparable to the primary objective.
2. To evaluate the rationale for volatile marker testing in exhaled breath for early
identification of lesions in the stomach as well as other conditions related to increasedrisk.
3. To evaluate the role of diet, lifestyle factors, and environmental factors in thedevelopment of gastric lesions.
4. To evaluate the impact of H. pylori eradication on selected medical conditions
potentially associated with the infection (e.g. obesity, inflammatory bowel disease,dementia, circulatory diseases, and oesophageal diseases).
3. Methods
Approximately 30 000 men and women will be recruited into a randomized study. Eligible
subjects aged 40–64 years at study entry who are residents in areas with high gastric cancer
incidence will be invited to participate in the trial by visiting one of the study clinics set up
specifically for this trial.
For eligible participants who agree to participate and sign the informed consent, a risk factor
questionnaire will be administered and a complete medical evaluation will be performed atbaseline.
Participants will be randomly assigned to either Group 1 (50%) or Group 2 (50%). Among
those assigned to Group 1, H. pylori screening by detecting immunoglobulin G (IgG) groupantibodies in plasma/serum and pepsinogen testing will be performed. According to theresults of the tests, participants will be assigned to H. pylori eradication treatment or upper
endoscopy. Participants with serological evidence of atrophic gastritis (low pepsinogen I/II
ratio) will undergo upper endoscopy with appropriate biopsy sampling as well as further
follow-up with endoscopy according to the MAPS (Management of precancerous conditions
and lesions in the stomach) guidelines. H. pylori-positive individuals will be offered standard
eradication treatment as appropriate. From subjects in this group, breath samples will also
be collected by research nurses or junior physicians, for the study of volatile markers.
Participants assigned to Group 2 (50%) will constitute the control group, after having had a
medical evaluation at the time of recruitment. During the follow-up period, this group will beoffered a consultation with a specialist when required due to clinical symptoms.
Participants in both Group 1 and Group 2 will be offered faecal occult blood testing (FOBT)
as a benefit of study participation. Any participants with a positive FOBT result will bereferred for colonoscopy.
All the trial participants, including those in Group 2, will be followed up at least for 15 years
to collect systematic information on medical conditions, in particular gastric cancer andcause of death. A follow-up telephone call or alternative communication will be made every
5 years for outcome assessment.
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The general study will be preceded by a pilot study to test the assumptions as well as thetools and functionality of the study infrastructure. On completion of the pilot phase, therequired infrastructure and tools planned in the general study will be adapted accordingly.
4. End-points
The primary end-point for this trial will be the difference in mortality from gastric cancer
between Group 1 and Group 2 at 15 years or when enough cases have accumulated todemonstrate a statistical difference between the groups.
In addition to the difference in gastric cancer mortality between the two groups, other endpoints required to achieve the secondary objectives are:
 The difference in gastric cancer incidence between Group 1 and Group 2
 The difference in all-cause mortality between Group 1 and Group 2
 The difference in incidence and mortality of medical conditions between Group 1 andGroup 2 The sensitivity and specificity of pepsinogen tests to detect atrophy The proportion of gastric cancers arising in patients with non-atrophic versus atrophic
gastritis
 The proportion of cancers arising in patients with atrophy but negative for H. pylori
infection The difference in incidence of gastric cancer between the group with successful
eradication and those within Group 1 who refused eradication therapy or in whom
eradication therapy failed
 The proportion of gastric cancer cases identified during scheduled follow-up
endoscopy out of the total number of cases in the follow-up group
 The differences in the test performance and disease prevalence between ethnic
groups The performance (sensitivity, specificity, overall accuracy) of the volatile marker
testing approach to diagnose gastric cancer as well as premalignant lesions in thestomach.
5. Statistical analysis
The estimates of differences in gastric cancer-related mortality between the groups havebeen based on the cancer incidence in eastern Europe (e.g. Belarus) according to the
GLOBOCAN 2008 data [17].
With 90% power and a significance level of 5%, significant differences between the groups
are expected to be achieved after 15 years of follow-up.
6. Pilot study
Before embarking on the large-scale intervention, a 2000–3000-subject pilot study will be
conducted in one or more potential sites. To date the pilot has been launched in Latvia. All
the procedures described for the main study will be implemented during the pilot, except thelong-term follow-up. The general objectives of the pilot study are to test the assumptions, theappropriateness of the chosen tools, and the infrastructure before the launch of the general
study.
The objectives of the pilot study are:
1. To test the assumptions defined for the study, as far as the short-duration pilot canaddress these (e.g. the mortality-related assumptions cannot be addressed with thepilot).
150

2. To test the appropriateness of the chosen tools (e.g. questionnaire, approach to thestudy population recruitment, laboratory investigations).
3. To test the appropriateness of the chosen infrastructure for the study (e.g. online data
capture system; infrastructure for sample procurement, transportation, and storage;
result reporting).
The concrete aims of the pilot study are to evaluate:
1. The acceptance rate of the target population to participate in the study
2. The proportions of male and female participants
3. The proportions of participants in the different age groups
4. The number of cases that could be recruited by a stationary or mobile recruitment
centre per day or per week
5. The prevalence of alarm symptoms or other exclusion factors for the study in the study
population
6. The prevalence of H. pylori in the study population
7. The sensitivity and specificity of pepsinogen tests as measured by different methods(latex agglutination, enzyme-linked immunosorbent assay [ELISA]) to detect moderate
to severe atrophy in the stomach
8. The rationale of gastrin-17 test use for identification of atrophy in the antral part of thestomach in the general study
9. The rationale of cancer autoantibody test panel use for identification of gastric cancer
cases in the general study
10. The acceptance rate to undergo H. pylori eradication if the infection is positive
11. The acceptance rate to undergo upper endoscopy if the pepsinogen test is positive
12. The adherence to the H. pylori eradication treatment
13. The efficacy of a 10-day triple clarithromycin-containing eradication regimen
14. The differences between the target populations in different recruitment sites
15. The differences in acceptance rates by age and sex
16. The feasibility of the data capture system
17. The feasibility of the approach for randomization
18. The feasibility of the laboratory testing approach
19. The adherence to the upper endoscopy protocol
20. The feasibility of sample logistics, including cross-border transportation
21. The ability to comply with the local legal requirements
22. The impact of eradication on short-term outcomes, including biomarkers.
In contrast to the general study, the pilot will also include a gastric-cancer specificautoantibody panel and detection of gastrin-17. Also, the performance of different
pepsinogen tests (different methods) will be compared in the pilot study.
For the purpose of measuring the sensitivity and overall accuracy of the non-invasive tests, agroup of controls with normal blood test results will be also referred for upper endoscopy.
The design of the pilot study is reflected in Fig. 4.2.1.

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Fig. 4.2.1. General design of the pilot study. FIT, faecal immunochemical test; G-17, gastrin-17; HP,
Helicobacter pylori; MAPS, Management of precancerous conditions and lesions in the stomach; Pep,
pepsinogen; PgI, pepsinogen I; PgII, pepsinogen II. * All patients with positive gastric cancer-related
autoantibodies will be referred for upper endoscopy. ** Based on volatile marker test results, referral
for upper endoscopy will be done only if specific panel characteristics for gastric cancer are revealed.

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2. Malfertheiner P, Megraud F, O’Morain CA, Atherton J, Axon AT, Bazzoli F, et al.;European Helicobacter Study Group (2012). Management of Helicobacter pylori
infection–the Maastricht IV/Florence Consensus Report. Gut. 61(5):646–64.
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3. Areia M, Carvalho R, Cadime AT, Rocha Gonçalves F, Dinis-Ribeiro M (2013). Screening
for gastric cancer and surveillance of premalignant lesions: a systematic review of costeffectiveness studies. Helicobacter. 18(5):325–37. http://dx.doi.org/10.1111/hel.12050
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Helicobacter pylori for gastric cancer prevention. Best Pract Res Clin Gastroenterol.
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6. Hattori Y, Tashiro H, Kawamoto T, Kodama Y (1995). Sensitivity and specificity of mass
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7. Kikuchi S, Kato M, Katsuyama T, Tominaga S, Asaka M (2006). Design and planned
analyses of an ongoing randomized trial assessing the preventive effect of Helicobacter
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Chapter 4.3
Effect of Helicobacter pylori eradication on gastric cancer
prevention in the Republic of Korea: a randomized controlled
clinical trial
Il Ju Choi, Jin Young Park, and Rolando Herrero
The incidence of gastric cancer in the Republic of Korea is currently the highest in the worldand has remained stable for decades without geographical variation across the country. In
the most recent statistics, from 2010, gastric cancer remains the leading cause of cancer inthe Republic of Korea and is the third leading cause of cancer death in men (agestandardized incidence rate, 62.3 per 100 000 person-years; age-standardized mortality
rate, 20.7 per 100 000 person-years) [1]. In the Republic of Korea, the seropositivity rate of
Helicobacter pylori in 2005 was 59.6% among subjects older than 16 years who had neither
a history of H. pylori eradication nor current gastrointestinal symptoms [2].
Considering the high prevalence of H. pylori in the Republic of Korea, H. pylori screening
and eradication may potentially reduce gastric cancer incidence and mortality. The National
Cancer Screening Program (NCSP) currently provides universal secondary prevention by
providing endoscopic or radiological screening every 2 years rather than primary prevention
measures for H. pylori eradication.
The International Agency for Research on Cancer (IARC) classified H. pylori as a Group 1
carcinogen in 1994 [3], and reconfirmed this evaluation in 2009 [4]. In many geographicalregions, consensus guidelines for H. pylori management have been reported [5–9]. Strongly
supported by data from the literature, these guidelines consistently recommend H. pylori
eradication for patients with peptic ulcer diseases and mucosa-associated lymphoid tissue(MALT) lymphoma. However, for prevention of gastric cancer, recommendations for H. pylori
eradication are not consistent among the guidelines, except for eradication after endoscopic
resection of gastric cancer. The second Asia-Pacific guidelines recommended a screen-andtreat strategy for H. pylori infection in communities with a high incidence of gastric cancer [8].
However, guidelines for the Republic of Korea, which were revised in 2013, do not provide
any statement regarding H. pylori management for the general population. Based on theavailable evidence, these guidelines only provided a strong recommendation for H. pylori
eradication after endoscopic resection of early gastric cancer and weak recommendations
for patients with atrophic gastritis or intestinal metaplasia and a family history of gastriccancer [5].
Standard triple therapy consisting of a proton pump inhibitor (PPI), amoxicillin, andclarithromycin is recommended as a primary regimen for H. pylori eradication in the Republicof Korea [5]. However, there has been a decreasing rate of H. pylori eradication withstandard triple therapy in the Republic of Korea since 2000. Eradication success rates havebeen reported to be 74.0–80.4% with a 14-day triple therapy [10, 11] and 64.9–76.9% with a
7-day triple therapy [11–13]. The decreasing rates of H. pylori eradication by standard triple
therapy may be due to the high rate of clarithromycin resistance. Meanwhile, bismuthcontaining quadruple therapy, which is recommended as a secondary regimen for H. pylori
eradication, remains effective, with higher success rates than standard triple therapy. The
success rates of H. pylori eradication by secondary quadruple therapy have been reported tobe 85.1–96.3% with a 14-day treatment and 81.6–83.5% with a 7-day treatment [14–16].

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To address the issues of population-based prevention strategies, it is proposed to conduct a
multicentre, double-blind, randomized controlled trial in the Republic of Korea to evaluate theeffect of H. pylori eradication to prevent gastric cancer in middle-aged adults. The study will
also evaluate the effects of H. pylori eradication on the incidence of gastric dysplasia andother conditions that may be associated with H. pylori infection. Possible adverse events
caused by antibiotic treatment as well as the role of environmental and host genetic factors
in the development of gastric cancer and its precursors, and as modifiers of the treatment,
will also be assessed. All participants will be followed up for at least 10 years to assess thegastric cancer incidence in both the intervention and placebo groups, as well as in the H.
pylori-negative group.
1. Objectives of the study
H. pylori infection is an important cause of gastric cancer. Therefore, the hypothesis is thatthe risk of gastric cancer can be reduced by eradication of H. pylori infection in individuals in
the Republic of Korea. The primary objective of the study is to determine whether H. pylori
eradication reduces gastric cancer incidence in a population of subjects aged 40–60 years in
the Republic of Korea.
The secondary objectives are:
1. To determine whether H. pylori eradication reduces the incidence of gastric dysplasia
2. To assess adverse events caused by antibiotic treatment for H. pylori eradication
3. To evaluate the impact of H. pylori eradication on the occurrence of selected medical
conditions potentially associated with the infection or its eradication
4. To assess whether the H. pylori treatment results in similar incidences/mortalities ofgastric cancer compared with the unexposed group without H. pylori infection
5. To assess differences in gastric cancer incidence and mortality between the groups
with successful eradication and with persistent H. pylori infection
6. To assess the impact of H. pylori eradication on precancerous lesions (atrophy score
and intestinal metaplasia)
7. To investigate the role of cofactors for gastric cancer development among untreated
H. pylori-positive subjects (e.g. demographics, dietary differences, lifestyles, hostgenetic factors, and inflammatory markers).
2. Overview of the study design
This is a population-based, double-blind, randomized controlled clinical trial that will be
conducted in seven designated hospitals participating in the NCSP in different administrative
districts in the Republic of Korea. The overview of the study design is illustrated in Fig. 4.3.1.
Men and women aged 40–60 years at entry who were invited to the NCSP in the Republic ofKorea will be asked to participate in this trial until a total of 11 000 individuals have been
recruited. Eligible participants who agree to participate and sign informed consent will
provide a medical history, undergo a physical examination, and be administered a detailed
lifestyle questionnaire. The subjects will be excluded if they meet any of the following criteria:(i) a previous history of gastric cancer, (ii) a family history of gastric cancer in a first-degree
relative, (iii) other organ cancers within 5 years, (iv) indication of H. pylori eradiation such as
peptic ulcer or MALT lymphoma, or (v) other serious medical illnesses or conditions that
preclude adequate participation. All participants will undergo upper endoscopy at entry, anda standard collection of gastric biopsies will be performed for histology and H. pylori
diagnosis. H. pylori status will be determined through the rapid urease test (RUT) andhistological examination on endoscopic biopsy specimens. The pathological results of biopsy
specimens will be reported based on the updated Sydney system [17].

155Fig. 4.3.1. Overview of the study design. GC, gastric cancer; GORD, gastro-oesophageal reflux
disease; HP, Helicobacter pylori.

Subjects who are H. pylori-positive (~6600 with a H. pylori prevalence estimate of 60%) will
be randomly assigned to either the intervention group (Group 1) (50%) or the placebo group(Group 2) (50%). For those assigned to Group 1, an eradication treatment with a 10-day
course of a bismuth-based quadruple therapy will be provided. The regimen consists of
500 mg of metronidazole (3 times a day), 500 mg of tetracycline (4 times a day), and 300 mg
of bismuth (4 times a day), and a PPI (twice a day) for 10 days. Participants assigned toGroup 2 will receive a placebo with an identical shape. This regimen has been selected dueto the low eradication rates (< 80%) in the Republic of Korea of the standard triple therapy,
which consists of a PPI, amoxicillin, and clarithromycin [12, 18]. Currently, clarithromycin
resistance rates of H. pylori are greater than 20% in the Republic of Korea [19, 20]. Both theMaastricht IV/Florence Consensus Report [6] and recent guidelines for the Republic ofKorea for H. pylori infection [5] recommend a bismuth-containing quadruple therapy as afirst-line treatment regimen for H. pylori eradication in areas with high clarithromycin
resistance (clarithromycin resistance rate > 15–20%). Eradication success rates of a156bismuth-containing quadruple therapy have been reported to range from 83% to 100% as afirst-line therapy and from 91% to 100% as a second-line therapy (National Cancer Center
data, personal communication). This regimen was therefore chosen for H. pylori eradicationin this study.
Randomization will be performed using a permuted block design stratified by sex and thecentre location. Both participants and investigators will be blinded to the interventions.
Participants with no evidence of H. pylori infection or baseline chronic atrophic gastritis will
constitute the “unexposed group” as a comparison group for investigating the natural historyof the H. pylori-infected or treatment group. Data will be entered into the Internet-based
eVelos system operated by the National Cancer Center, which serves the research teamthrough a centralized platform.
All the trial participants will be followed up within the NCSP with endoscopy every 2 years forat least 10 years. Gastric cancer cases will be identified during a biennial endoscopic followup appointment for those who participated in the screening programme. For those lost to
endoscopic follow-up, gastric cancer cases will be identified through a record linkage with
the Korea Central Cancer Registry. At the first follow-up visit during routine screening, twobiopsies will be collected (antrum and body) for blinded assessment of the presence of H.
pylori using the RUT method. After 10 years, at the end of the study, endoscopic biopsies toassess the presence of precancerous lesions will be obtained, and interviews andspecimens similar to those obtained during the enrolment visit will be obtained. It is
anticipated that approximately 90% of all participants will undergo upper endoscopy every
2 years as part of the NCSP, assuming an active follow-up schedule.
3. Statistical considerations
The expected number of gastric cancer cases was calculated based on the assumption of areduction in gastric cancer incidence due to the intervention of at least 47%. The assumption
for the effect size is based on the available literature [21] as well as on the most recent
Japanese study of early gastric cancer patients, which reported a hazard ratio of 0.497 (95%
confidence interval, 0.297–0.831) after a maximum of 10 years of follow-up in the eradicatedgroup for the incidence of metachronous gastric cancer after endoscopic resection [22].
Applying a significance level of 5% and a statistical power of 90%, 104 gastric cancer cases
would be needed. Overall gastric cancer incidence (men and women combined) in an H.
pylori-positive population in the Republic of Korea was calculated as 165 cases per 100 000
population each year, using the most recent 5-year follow-up data from the NCSP. H. pylori
prevalence was estimated to be 60% in adults aged 40–60 years in the Republic of Korea[2], and a relative risk of gastric cancer for H. pylori-positive to H. pylori-negative patientswas assumed to be 6, based on available evidence from the literature [23]. Assuming a 10%
follow-up loss, it was estimated that the total sample size of 11 000 (6600 H. pylori-positive
participants in both Groups 1 and 2 plus 4400 participants in the H. pylori-negative group),with all participants to be followed up for 10 years, would meet the requirement of the study
design to investigate the differences of at least 47% in the gastric cancer incidence rate
between the treatment and placebo groups.
The primary analysis will be based on intention to treat; therefore, all randomized subjects
will be included in the analysis regardless of compliance with treatment. Information oninterruptions, changes, or discontinuation of treatments will be documented and used toperform additional analyses that are restricted to subjects who completed the treatments. A
per-protocol analysis will also be performed with data obtained from subjects who complete
this trial. Independent statisticians will prepare the interim unblinded reports for the
independent data and safety monitoring committee, which will oversee participant safety andthe quality of the trial. The study will be coordinated jointly by the National Cancer Center inthe Republic of Korea and the Prevention and Implementation Group at IARC.
157

4. Ethical considerations
The current guidelines in the Republic of Korea do not include routine H. pylori testing anderadication, except for patients with a history or treatment of early gastric cancer, and thosewith peptic ulcer or MALT lymphoma [5]. The randomized clinical trial design is considered to
be ethically sound for the following reasons:
1. The impact of eradication on gastric cancer incidence in the Republic of Korea has notbeen completely elucidated.
2. H. pylori treatment is not a standard practice in the Republic of Korea for the general
population; therefore, the National Health Insurance does not cover the cost oftreatment.
3. All participants are recruited within the context of the NCSP in the Republic of Korea,
which provides active surveillance every 2 years for detection of cancer at an earlystage, when it is curable.
4. H. pylori infection will be treated in participants with early gastric cancer, peptic ulcer(benign gastric ulcer or duodenal ulcer), and MALT lymphoma detected during theendoscopic follow-up visit, as indicated in the guidelines.
5. Conclusions
Despite much evidence supporting the association between H. pylori infection and gastriccancer, it remains controversial whether H. pylori eradication may reduce or prevent gastriccancer occurrence in the general population. Moreover, recent reports suggest that H. pylori
plays a mixed role in human health and is not a major risk factor for all-cause mortality [24].
Currently, there are two opposite viewpoints on this issue. One is “It’s time to eradicate
gastric cancer by treating H. pylori” [25]; the other is “Stop killing beneficial bacteria by
antibiotic overuse”, which raised concerns about permanent changes in our protective
microflora [26]. The results of several ongoing studies on the effectiveness of H. pylori
eradication are now being eagerly awaited [27]. It is anticipated that it will be possible to findanswers to those critical and important issues by conducting a well-designed, multicentre
study in the Republic of Korea, coordinated by the National Cancer Center in collaboration
with IARC. Success of this primary prevention strategy for gastric cancer in the general
population may benefit not only those in the Republic of Korea but also those in high-riskcountries where endoscopic surveillance is not under consideration for decreasing gastriccancer burden.

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160

Chapter 4.4
Community-based Helicobacter pylori eradication with twosequential antibiotic regimens for the residents and migrants in ahigh-risk area for gastric cancer
Yi-Chia Lee
In Taiwan, China, programmatic gastric cancer prevention was started in 2004 for a high-risk
population on an offshore island (Matsu Island), applying a strategy of mass eradication of
Helicobacter pylori. This chapter provides a detailed rationale for this population-based
study, addressing the burden of gastric cancer, design of the preventive programme, methodof invitation to participants, screening test, antibiotic treatment, endoscopic examination,
evaluation method, and the updated results.
1. Gastric cancer burden in Matsu Island
Matsu Island is an archipelago of five major islands in the Taiwan Strait, located about
100 miles from the coast of Taiwan, China, near the northern coast of Fujian Province inmainland China (Fig. 4.4.1). The population of Matsu Island was about 5000 in 1995 andgradually increased to about 10 000 by 2008. Before 2004, the incidence rate of gastriccancer in Matsu Island was about 50 per 100 000 person-years (Table 4.4.1), which was 3–5
times the incidence rate in the main island of Taiwan, China. The mortality rate of gastriccancer was about 26 per 100 000 person-years, yielding a mortality-to-incidence ratio of
about 0.5. An effective preventive strategy was urgently needed for this high-risk population.
2. Design of a gastric cancer preventive programme in Matsu Island
To prevent gastric cancer in Matsu Island, a secondary preventive programme was
implemented during 1995–1998. The intervention applied a two-stage design. The first stagecomprised a standardized questionnaire and serum pepsinogen measurement, aiming to
identify high-risk subjects, and the second stage included endoscopic examination for
subjects with a positive serum pepsinogen measurement [2, 3]. However, the sensitivity andspecificity of pepsinogen measurement in identifying subjects with premalignant lesions were
estimated to be 62% and 70%, respectively. Because the programme’s effectiveness waslow, it was ended in 1999. During 1999–2003, no intervention for gastric cancer prevention
was administered. Also during this period, accumulated evidence showed that H. pylori
infection was the major cause of gastric cancer [4, 5], which prompted the planning of amass eradication programme.

161

Fig. 4.4.1. Location of Matsu Island and prevalence of Helicobacter pylori infection. Matsu Island is anarchipelago of five major islands; the prevalence of H. pylori infection on each island is specified. Notethat Fujian Province in mainland China was also an area with prevalent H. pylori infection and a highgastric cancer incidence rate. Source: Lee et al. (2013) [1].

162

Table 4.4.1. Number of people at risk, number of incident cases, number of deaths, and incidence
and mortality rates of gastric cancer in Matsu Island, 1995–2010aYear

Population

New gastriccancer cases

Gastric cancer
deathsIncidence rate

1995

5711

4

2

70.04

35.02

1996

5959

5

3

83.91

50.34

1997

7240

5

3

69.06

41.44

1998

7536

4

1

53.08

13.27

1999

6560

4

2

60.98

30.49

2000

6733

2

3

29.70

44.56

2001

8851

6

3

67.79

33.89

2002

8763

1

0

11.41

0

2003

8806

3

0

34.07

0

2004

9359

9

3

96.16

32.06

2005

10 345

1

3

9.67

29.00

2006

9786

2

3

20.44

30.66

2007

9965

2

2

20.07

20.07

2008

9961

1

2

10.04

20.08

2009

9919

3

3

30.25

30.25

2010

9944

0

2

0

20.11

a

Mortality rate

Rates are per 100 000 person-years.

Source: Adapted from Lee et al. (2013) [1].

In 2004, under the auspices of the Taiwanese Ministry of Health, a mass eradication
programme for H. pylori was launched (NCT00155389), aiming to prevent gastric cancer andreduce its mortality rate in this population [6]. This prospective cohort study applied quasiexperimental, before-and-after study design, designating the whole population of Taiwan,
China as an external comparator group. The main outcome measure was the impact ofmass eradication on the changes of premalignant gastric lesions and gastric cancer, which
was obtained by comparing data from the periods before and after the mass eradication
programme in the same population. The eligible age range for participation in the study was
30 years and older (n = ~5000), registered in the Matsu Island population list. It should be
noted that the Matsu Island population was not a closed population; some subjects
registered in the population list may have migrated to the main island of Taiwan, China.
These migrants from Matsu Island were also invited to participate in screening. Pregnant or
lactating women, patients with major concomitant diseases, and those who had undergone
gastric surgery were excluded. To date, three rounds of mass screening have been
conducted in this population: in 2004–2005, 2008–2009, and 2012–2013.
163a3. Invitation method
During 1999–2003, a multiple-disease screening programme was launched that included
non-neoplastic diseases (e.g. diabetes mellitus, hypertension, and hyperlipidaemia) andneoplastic diseases (e.g. cervical, breast, and colorectal cancers), but not gastric cancer.
This programme was called the Matsu Community-Based Multiple Screening Program [7]. In
this multiple-disease screening programme, potential participants were contacted by
telephone and then received a pamphlet by mail that invited them to visit their local
screening centres.
In 2004, the mass eradication programme, which included the first stage with the 13C-urea
breath test (13C-UBT) and a structured questionnaire, and the second stage with endoscopic
examination, was appended to the multiple-disease screening programme. The
questionnaire included sociodemographic characteristics; cigarette smoking, alcohol
consumption, and exercise habits; personal and familial history of major diseases; andintake frequency of salted foods, pickled foods, meat, and fruit.
4. 13C-UBT and antibiotic treatment
The sensitivity and specificity of 13C-UBT in diagnosing H. pylori infection were estimated to
be 97.8% and 96.8%, respectively [8]. During the first round (2004–2005) and second round(2008–2009) of mass screening, individuals with positive 13C-UBT results underwent
endoscopic screening and antibiotic treatment, including: 7-day triple therapy (40 mg of esomeprazole once a day, 1 g of amoxicillin twice aday, and 500 mg of clarithromycin twice a day), and 10-day levofloxacin-based triple therapy (40 mg of esomeprazole once a day, 1 g ofamoxicillin twice a day, and 500 mg of levofloxacin once a day) for individuals inwhom initial treatment failed.
The 13C-UBT was done 6–8 weeks after antibiotic treatment. For individuals whose results
remained positive after two courses of antibiotic treatments, no further empirical treatment
was given.
During the third round (2012–2013), those who tested positive were invited to participate in arandomized controlled trial (NCT01607918) that compared two first-line antibiotic regimens,
including: 14-day triple therapy (30 mg of lansoprazole twice a day, 1 g of amoxicillin twice aday, and 500 mg of clarithromycin twice a day, for 14 days), and 10-day sequential treatment (30 mg of lansoprazole and 1 g of amoxicillin twice a day
for days 1–5, followed by 30 mg of lansoprazole, 500 mg of clarithromycin, and
500 mg of metronidazole twice a day for days 6–10).
Individuals in whom initial treatment failed received 10-day levofloxacin-based triple therapy(30 mg of lansoprazole twice a day, 1 g of amoxicillin twice a day, and 500 mg oflevofloxacin once a day).
5. Endoscopy
Biopsy specimens from the antrum (from the greater and lesser curvatures 2–3 cm from thepylorus) and specimens from the corpus (one from the lesser curvature and one from thegreater curvature at the mid-corpus) were obtained during endoscopy. Specimens were
graded using a visual analogue scale (the modified Sydney classification) to rate the severityof each category as none (0), mild (1), moderate (2), or marked (3). Three subcategories
were added to describe the types of inflammatory cell infiltrates, including acuteinflammation, chronic inflammation, and mucosa-associated lymphoid tissue (MALT). The
presence and severity of gastric dysplasia were also graded as none, indefinite fordysplasia, low-grade dysplasia, and high-grade dysplasia.
164

6. Evaluation method
Knowing that new immigrants or the younger generation would enter this cohort or meet theeligibility criteria, an inter-screening interval of 4 years was scheduled. The follow-up period
was set as at least 12 years. The aims of the three successive rounds were as follows.
6.1 First round (2004–2005)
 To demonstrate proof of concept.
 To evaluate the eradication rate of a test–treat–retest–retreat strategy in thecommunity.
 To perform an economic modelling study to simulate the long-term outcome.
6.2 Second round (2008–2009) To evaluate the effectiveness of intervention in terms of changes in theprevalence/incidence rate of H. pylori infection, premalignant gastric lesions, gastriccancer, and other upper gastrointestinal lesions (e.g. peptic ulcers and reflux
oesophagitis).
 To evaluate the reinfection rate of H. pylori after eradication.
6.3 Third round (2012–2013)
 To optimize the eradication rate of antibiotic treatment.
 To evaluate the impact of mass eradication on the drug-resistance pattern of H. pylori
after two courses of interventions.
7. Results
7.1 First round (2004–2005)
A total of 4121 participants participated, and 2598 (63%) tested positive for H. pylori
infection. Endoscopy was performed for 1762 H. pylori-positive individuals, and 4 gastriccancers were found. The eradication rates with first-line therapy were 86.9% and 88.7% byintention-to-treat and per-protocol analyses, respectively. Rescue therapy eradicatedinfection in 91.4% of 105 non-responders. The overall eradication rate was 97.7% after two
courses of antibiotic treatments [6]. Using the first-round result as the base case, a cost–effectiveness analysis was performed to predict long-term effectiveness. The results showedthat mass eradication was cost-effective. The incremental cost–effectiveness ratio for onceonly mass eradication at age 30 years versus no screening was US$ 17 044 per life-year
gained. Sensitivity analyses showed that the cost–effectiveness was subject to the rate ofreinfection, the endoscopic detection rate of early gastric cancer, and the age at initial
screening [9].
7.2 Second round (2008–2009)
In this round, mainly those who had participated in the first round were invited, to evaluate
the effectiveness in reducing premalignant gastric lesions and the reinfection rate of H.
pylori. A total of 1334 subjects participated (1152 who had participated in the first round, and
182 new participants). Overall, the prevalence rate of H. pylori infection was 13.4% (9.7% of
the group of first-round participants who were retested in the second round, and 36.8% of
the group of new participants). During 2004–2008, the incidence of reinfection was 1% (95%
confidence interval [CI], 0.6–1.4%) per person-year. Of the 1762 residents who had
undergone a baseline histological assessment in 2004, 841 underwent endoscopy in thesecond round and 1 gastric cancer was found. To evaluate the effectiveness of theintervention, three different analyses were used, as follows [1]:
 A comparison of the prevalence and incidence rates between the periods before andafter the mass eradication.
165



A comparison of the severity scores of intragastric histology before and after themass eradication.
 A comparison of the observed and predicted data using the time trends before andafter the mass eradication.
First, the prevalence and incidence rates were compared by comparing data between the 5year periods before and after chemoprevention. The results showed that the effectiveness of
reducing the incidence of gastric atrophy was significant, at 77.2%, whereas the reduction in
intestinal metaplasia or dysplasia was not significant. The reduction in gastric cancer
incidence was 25%. The reduction in peptic ulcer disease was 67.4%, whereas theincidence of oesophagitis was 6% after treatment.
Second, the changes in the intragastric histology were evaluated. The descriptive results areshown in Tables 4.4.2–4.4.6. These results showed significant improvement in the severity
scores for acute inflammation, chronic inflammation, MALT, and gastric atrophy, but nochange in the severity score for intestinal metaplasia. Regression analyses showed thatsuccessful eradication of H. pylori was associated with a significant decrease in histologicalscores; however, this effect was modified by the individual’s age. Histological regression
after the eradication of H. pylori infection was more prominent in young adults. The impacts
of individual factors were also evaluated, using multiple logistic regression analyses. The
factors of interest included age, smoking, alcohol consumption, metabolic risk factors, andfirst-degree relatives with gastric cancer. The results consistently showed that greater age
was associated with the occurrence of intestinal metaplasia after H. pylori treatment.
Third, taking into consideration the improved sanitation and hygiene applied during the study
period, the data on gastric atrophy, intestinal metaplasia, and the incidence and mortality
rates of gastric cancer between 1995 and the end of 2003 (the historical control data) wereused to formulate the Poisson regression model. Then, the occurrence of premalignant
gastric lesions and gastric cancer between 2004 and the end of 2008 was predicted, if noscreening was implemented. The results consistently showed that the effectiveness of
reducing the incidence of gastric atrophy was significant, at 61%. No significant benefit wasseen for intestinal metaplasia, gastric cancer incidence, or gastric cancer mortality.

166

Table 4.4.2. Scores of acute polymorphonuclear infiltrates in Matsu Island before chemoprevention (first data, in 2004) and after chemoprevention (second
data, in 2008). An excess of cases below the diagonal line indicates an improvement in histological scores between the two rounds of eradication.
Follow-up score of acute polymorphonuclear infiltrates (antrum, body)

Baseline
score

(0,0)

(0,1)

(0,2)

(0,3)

(1,0)

(1,1)

(1,2)

(1,3)

(2,0)

(2,1)

(2,2)

(2,3)

(3,0)

(3,1)

(3,2)

(3,3)

Total

(0,0)

52

0

0

1

1

1

0

0

0

2

0

0

0

0

0

0

57

(0,1)

9

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

10

(0,2)

5

1

0

0

1

0

0

0

0

0

0

0

0

0

0

0

7

(0,3)

2

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

2

(1,0)

125

1

0

0

12

5

0

0

2

1

1

0

0

0

0

0

147

(1,1)

111

3

1

0

6

5

0

0

2

3

1

0

0

0

1

0

133

(1,2)

24

1

0

0

0

1

0

0

0

1

0

0

0

0

0

0

27

(1,3)

10

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

10

(2,0)

93

1

0

0

6

1

0

0

0

0

0

0

0

0

0

0

101

(2,1)

131

1

0

0

6

5

0

0

1

1

0

0

0

0

0

0

145

(2,2)

74

3

0

0

4

3

0

0

1

0

1

0

0

0

0

0

86

(2,3)

6

1

0

0

0

1

0

0

0

0

0

0

0

0

0

0

8

(3,0)

7

0

0

0

3

0

0

0

0

0

0

0

0

0

0

0

10

(3,1)

34

1

0

0

5

1

0

0

0

0

0

0

0

0

0

0

41

(3,2)

25

0

0

0

1

3

0

0

0

0

0

0

0

0

0

0

29

(3,3)

24

0

0

0

0

2

0

0

0

1

0

0

1

0

0

0

28

Total

732

13

1

1

45

29

0

0

6

9

3

0

1

0

1

0

841

167

Table 4.4.3. Scores of chronic lymphoplasmacytic infiltrates in Matsu Island before chemoprevention (first data, in 2004) and after chemoprevention(second data, in 2008). An excess of cases below the diagonal line indicates an improvement in histological scores between the two rounds oferadication.
Baselinescore

Follow-up score of chronic lymphoplasmacytic infiltrates (antrum, body)
(0,0)

(0,1)

(0,2)

(0,3)

(1,0)

(1,1)

(1,2)

(1,3)

(2,0)

(2,1)

(2,2)

(2,3)

(3,0)

(3,1)

(3,2)

(3,3)

Total

(0,0)

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

(0,1)

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

1

(0,2)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(0,3)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(1,0)

0

0

0

0

8

0

0

0

0

0

0

0

0

0

0

0

8

(1,1)

7

0

0

0

8

15

0

0

1

0

0

0

0

1

0

0

32

(1,2)

0

0

1

0

4

2

1

0

0

0

0

0

0

0

0

0

8

(1,3)

0

0

0

0

0

2

0

0

0

0

0

0

0

0

0

0

2

(2,0)

0

0

0

0

4

3

0

0

0

2

0

0

0

0

0

0

9

(2,1)

23

0

0

0

59

61

0

0

4

25

11

1

0

3

5

0

192

(2,2)

27

5

1

0

89

160

14

0

9

76

32

1

0

5

10

3

432

(2,3)

0

0

0

0

2

11

3

0

0

4

5

0

0

0

2

0

27

(3,0)

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

1

(3,1)

2

0

0

0

8

8

0

0

1

3

1

0

0

0

0

0

23

(3,2)

4

1

0

0

15

26

0

0

2

15

4

1

0

0

1

2

71

(3,3)

1

0

0

0

9

13

1

0

0

7

2

0

0

1

0

0

34

Total

65

6

2

0

207

302

19

0

17

132

55

3

0

10

18

5

841

168

Table 4.4.4. Scores of gastric atrophy in Matsu Island before chemoprevention (first data, in 2004) and after chemoprevention (second data, in 2008). An
excess of cases below the diagonal line indicates an improvement in histological scores between the two rounds of eradication.
Follow-up score of gastric atrophy (antrum, body)

Baseline
score

(0,0)

(0,1)

(0,2)

(0,3)

(1,0)

(1,1)

(1,2)

(1,3)

(2,0)

(2,1)

(2,2)

(2,3)

(3,0)

(3,1)

(3,2)

(3,3)

Total

(0,0)

54

1

0

0

7

7

0

0

0

2

1

0

0

0

0

0

72

(0,1)

4

2

0

0

1

1

0

0

0

0

0

0

0

0

0

0

8

(0,2)

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

(0,3)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(1,0)

184

6

0

0

45

8

0

0

0

0

0

0

0

0

0

0

243

(1,1)

131

8

3

0

38

15

2

0

1

1

0

0

0

0

0

0

199

(1,2)

23

5

0

0

8

2

0

0

0

0

0

0

0

0

0

0

38

(1,3)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(2,0)

51

2

0

0

12

4

0

0

3

0

0

0

0

0

0

0

72

(2,1)

65

6

0

0

31

15

1

0

0

0

1

0

0

0

0

0

119

(2,2)

39

4

1

0

12

6

3

0

0

0

0

0

0

0

0

0

65

(2,3)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(3,0)

2

0

0

0

2

0

0

0

0

0

0

0

0

0

0

0

4

(3,1)

9

0

0

0

2

1

0

0

0

0

0

0

1

0

0

0

13

(3,2)

3

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

4

(3,3)

0

1

0

0

2

0

0

0

0

0

0

0

0

0

0

0

3

Total

566

35

4

0

160

60

6

0

4

3

2

0

1

0

0

0

841

169

Table 4.4.5. Scores of mucosa-associated lymphoid tissue in Matsu Island before chemoprevention (first data, in 2004) and after chemoprevention(second data, in 2008). An excess of cases below the diagonal line indicates an improvement in histological scores between the two rounds oferadication.
Follow-up mucosa-associated lymphoid tissue score (antrum, body)

Baseline
score

(0,0)

(0,1)

(0,2)

(0,3)

(1,0)

(1,1)

(1,2)

(1,3)

(2,0)

(2,1)

(2,2)

(2,3)

(3,0)

(3,1)

(3,2)

(3,3)

Total

(0,0)

217

11

7

0

7

3

0

0

3

1

0

0

3

1

0

0

253

(0,1)

23

1

0

0

6

0

0

0

1

0

0

0

0

0

0

0

31

(0,2)

16

1

0

3

1

0

0

0

0

0

0

0

1

0

0

0

22

(0,3)

7

2

1

0

0

0

0

0

0

0

0

0

0

0

0

0

10

(1,0)

122

0

1

1

9

1

0

0

4

0

0

0

1

2

0

0

141

(1,1)

22

1

0

0

1

0

0

0

0

0

0

0

0

0

0

0

24

(1,2)

8

4

0

0

1

0

0

0

1

0

0

0

0

0

0

0

14

(1,3)

6

1

1

0

1

0

1

0

0

1

0

0

0

0

0

0

11

(2,0)

140

9

1

0

9

0

0

0

7

1

0

0

3

0

0

0

170

(2,1)

13

0

1

0

1

0

0

0

2

0

0

0

0

0

0

0

17

(2,2)

15

1

0

0

2

0

0

0

0

0

0

0

0

0

0

0

18

(2,3)

2

0

1

0

0

0

0

0

0

0

0

0

0

0

0

0

3

(3,0)

85

2

0

0

3

0

0

0

1

1

0

0

3

0

0

0

95

(3,1)

16

2

0

0

2

0

0

0

0

0

0

0

0

0

0

0

20

(3,2)

4

3

0

0

1

0

0

0

0

0

0

0

0

0

0

0

8

(3,3)

3

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

4

Total

699

38

13

4

45

6

1

0

19

4

0

0

11

3

0

0

841

170

Table 4.4.6. Scores of intestinal metaplasia in Matsu Island before chemoprevention (first data, in 2004) and after chemoprevention (second data, in2008). Similar case numbers above and below the diagonal line indicate no change in histological scores between the two rounds of eradication.
Follow-up score of intestinal metaplasia (antrum, body)

Baseline
score

(0,0)

(0,1)

(0,2)

(0,3)

(1,0)

(1,1)

(1,2)

(1,3)

(2,0)

(2,1)

(2,2)

(2,3)

(3,0)

(3,1)

(3,2)

(3,3)

Total

(0,0)

442

6

4

0

74

4

2

0

34

3

0

1

5

1

2

0

578

(0,1)

4

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

5

(0,2)

3

0

0

0

1

0

0

1

1

1

0

0

0

0

0

0

7

(0,3)

1

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

2

(1,0)

26

1

1

0

20

1

1

0

14

2

1

0

3

0

1

0

71

(1,1)

2

0

0

0

1

0

0

0

1

0

0

0

0

0

0

0

4

(1,2)

2

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

3

(1,3)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(2,0)

22

0

0

0

16

2

0

0

19

2

1

0

5

1

0

0

68

(2,1)

1

0

0

0

1

1

0

0

2

0

0

0

0

0

0

0

5

(2,2)

0

0

0

0

2

0

0

1

1

1

0

0

0

0

0

0

5

(2,3)

0

0

0

0

2

0

0

0

0

0

0

0

0

0

0

0

2

(3,0)

9

0

0

0

18

0

2

0

24

0

2

0

6

2

3

2

68

(3,1)

1

0

0

0

0

0

1

0

1

0

0

0

1

0

0

0

4

(3,2)

1

0

1

0

0

0

1

0

1

0

0

0

0

1

0

0

5

(3,3)

0

0

0

0

2

1

0

1

3

0

1

0

4

0

1

1

14

Total

514

7

6

0

138

10

7

3

101

9

5

1

25

5

7

3

841

171

7.3 Third round (2012–2013)
The main purpose of the third round was to optimize the efficacies of antibiotic treatment andto evaluate the issue of antibiotic resistance. A total of 2518 Matsu Island residents
participated (1480 who had participated in the first or second round, and 1038 newparticipants). A total of 713 people had positive 13C-UBT test results. The overall prevalence
rate of H. pylori infection was 28.3% (15.7% for former participants, and 46.2% for newparticipants). Using the data for 2008–2012, the reinfection rate was estimated to be 0.67%(95% CI, 0.45–0.98%) per person-year.
Among the 713 H. pylori-positive individuals, 509 received antibiotic treatment, 391 received
endoscopic examinations, and 382 received drug-susceptibility testing. No gastric cancer
was found. The preliminary results showed that two antibiotic regimens had similar efficacy
rates (about 87% and 89% for intention-to-treat and per-protocol analyses, respectively). As
shown in Table 4.4.7, preliminary data indicated that the drug-resistance patterns in the
Matsu Island population were 1.0% for amoxicillin, 8.2% for clarithromycin, 3.8% forlevofloxacin, 21.6% for metronidazole, and 0.3% for tetracycline, which were similar to thosein Taiwan, China [10].
In the third round, 362 adolescents (junior high school students; mean age, 14.4 years) werealso invited to receive the H. pylori stool antigen (HPSA) test, and the prevalence rate of H.
pylori infection in this group was 19.3%. Antibiotic treatment was not prescribed for theseadolescents.
Table 4.4.7. Impact of mass eradication of Helicobacter pylori on the prevalence rate of antibioticresistant strains in Matsu Island in 2013, compared with different geographical areas in Taiwan, China,
in the absence of mass screening
Location

Antibiotic
Amoxicillin

Clarithromycin

Levofloxacin

Metronidazole

Tetracycline

Matsu Island

1.0%

8.2%

3.8%

21.6%

0.3%

Northern Taiwan,
China

3.2%

8.1%

9.4%

21.8%

1.1%

Central Taiwan,
China

4.1%

10.3%

8.7%

23.9%

2.0%

Southern Taiwan,
China

1.5%

9.4%

13.8%

32.4%

2.2%

Eastern Taiwan,
China

0.9%

3.6%

2.7%

15.2%

4.5%

8. Conclusion
This cohort study demonstrated that mass eradication of H. pylori infection was applicable ina population in which H. pylori infection was prevalent and the incidence rate of gastriccancer was high. Significant benefit has been found in reducing gastric atrophy and the riskof peptic ulcer disease. It was anticipated that a substantial chemoprevention-mediatedreduction in gastric atrophy would lead to a further reduction in the incidence and mortality ofgastric cancer, provided that the follow-up period was sufficiently long and the Correa
pathway of pathological events leading to gastric cancer is valid. This study also lent support
to the concept of a “point of no return” at which the older participants who were more likely to172harbour intestinal metaplasia or dysplasia were less likely to benefit from anti-H. pylori
treatment for gastric cancer prevention. For the older adult population, endoscopic
surveillance was needed. Given the routine retest–retreatment practice, the drug-resistancepatterns did not show significant change in this population after two rounds of mass
eradication.

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9. Lee YC, Lin JT, Wu HM, Liu TY, Yen MF, Chiu HM, et al. (2007). Cost-effectivenessanalysis between primary and secondary preventive strategies for gastric cancer. Cancer
Epidemiol Biomarkers Prev. 16(5):875–85. http://dx.doi.org/10.1158/1055-9965.EPI-060758 PMID:17507609
10. Liou JM, Chen CC, Chen MJ, Chen CC, Chang CY, Fang YJ, et al.; Taiwan Helicobacter
Consortium (2013). Sequential versus triple therapy for the first-line treatment of
Helicobacter pylori: a multicentre, open-label, randomised trial. Lancet. 381(9862):205–
13. http://dx.doi.org/10.1016/S0140-6736(12)61579-7 PMID:23158886

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Chapter 4.5
The treatment of Helicobacter pylori infection of the stomach inrelation to the possible prevention of gastric cancer
Nicholas J. Wald
Although the incidence of gastric cancer is declining throughout the world, it remains acommon and serious global health problem. A strong association between the risk of gastriccancer and Helicobacter pylori infection, as judged by the assessment of H. pylori antibody
status, was first identified in prospective studies in 1991 [1]. Subsequently, the International
Agency for Research on Cancer judged the bacterium to be a cause of gastric cancer [2].
1. H. pylori infection and gastric cancer
H. pylori infection of the stomach is also common throughout the world. The infection isusually acquired in childhood, and is associated with living in relatively crowded conditions.
Its role in the etiology of gastric cancer probably involves co-factors, such as increased salt
consumption.
Interestingly, whereas a meta-analysis of 12 prospective studies [3] showed a relative risk of
2.4 (95% confidence interval [CI], 2.0–2.8) between H. pylori-positive status and gastriccancer, the relative risk was higher in individuals who were tested for infection more than
10 years before the development of the cancer (relative risk, 5.9) compared with those who
were infected 10 years or less before the development of the cancer (relative risk, 2.4). The
explanation for this difference is that H. pylori infection tends to be lost with the atrophic
gastritis that the organism causes. In other words, the bacterium over many years destroys
its own habitat.
From the relative risk estimates available, it can be concluded that in most parts of the world
most cases of gastric cancer are attributable to H. pylori infection.
2. Published trials of H. pylori eradication and gastric cancer
Three placebo-controlled trials of eradication therapy of H. pylori have been performed inrelation to the incidence of gastric cancer [4–6]. Two of the studies were performed in China,
and one in Japan. Fig. 4.5.1 shows that the summary relative risk was 0.64 (95% CI, 0.44–0.94). This summary estimate is dominated by the results from one study [6] with 34 casesof gastric cancer in the treated group and 52 in the placebo group, compared with 9 and 14,
respectively, in the two other studies. Another randomized controlled trial reported after
5 years [7] and 10 years [8] of follow-up, but after 10 years there were fewer cases of cancer
reported (9) than after 5 years (10). Because of this surprising result, this study was notincluded in the meta-analysis, but the relative risk was 0.65 (95% CI, 0.19–2.28) after
5 years and 0.29 (95% CI, 0.06–1.36) after 10 years.

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Fig. 4.5.1. Randomized placebo-controlled trials of eradication therapy on the incidence of gastriccancer in Helicobacter pylori-positive subjects. CI, confidence interval; RR, relative risk.

There are two published randomized placebo-controlled trials of eradication therapy inpatients with precancerous stomach lesions. One trial yielded a relative risk of 1.48 (95% CI,
0.25–8.83) [9]. The other trial had a four-group factorial design using two treatments: H.
pylori eradication treatment and the use of a COX-2 inhibitor (celecoxib) [10]. The incidencesof gastric cancer were as follows: placebo, 1/258; H. pylori treatment plus COX-2 inhibitor,
3/255; H. pylori treatment plus placebo, 3/255; and placebo plus COX-2 inhibitor, 2/256. The
relative risk based on the groups without use of the COX-2 inhibitor is 3.04 (95% CI, 0.32–
28.99), and the relative risk based on all the data (6/510 vs 3/514) is 2.00 (95% CI, 0.50–
7.97). Fig. 4.5.2 shows that the combined relative risk for these two trials is 1.79 (95% CI,
0.60–5.33).
Two randomized trials have been performed on H. pylori eradication therapy on theincidence of second gastric cancers, one in Japan and the other in the Republic of Korea[11, 12]. The two trials resulted in 19 second gastric cancers in the treated group comparedwith 41 in the control group (see Fig. 4.5.3). The relative risk estimate was 0.47 (95% CI,
0.28–0.80).

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Fig. 4.5.2. Randomized placebo-controlled trials of eradication therapy on the incidence of gastriccancer in Helicobacter pylori-positive subjects with precancerous lesions. CI, confidence interval; RR,
relative risk.

Fig. 4.5.3. Randomized placebo-controlled trials of eradication therapy on the incidence of a second
gastric cancer in Helicobacter pylori-positive subjects. CI, confidence interval; RR, relative risk.

Three studies compared the number of second gastric cancers between patients in whom H.
pylori had been successfully eradicated after treatment and patients in whom the treatment
had failed to eradicate H. pylori; relative risks of 0.59 (95% CI, 0.30–1.19) [13], 0.53 (95%CI, 0.32–0.87) [14], and 0.45 (95% CI, 0.23–0.86) [15] were observed. However, thesestudies were not randomized controlled trials, so the possibility of selection bias cannot be
excluded.

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These results, taken together, suggest that treating H. pylori infection of the stomach
protects against gastric cancer, but they do not provide conclusive evidence, mainly because
they are dominated by the results of one trial [6]. Given that other randomized trials are in
progress, it would be prudent to defer any conclusion as to the benefit of H. pylori
eradication therapy on gastric cancer until further evidence is available from these trials.
3. The H. pylori Screening Study
One trial in progress is the H. pylori Screening Study (HPSS) being conducted in the United
Kingdom, which addresses the question: Does H. pylori screening and the treatment of
those with positive results prevent gastric cancer, and if so, to what extent? The anti-H.
pylori treatment used was 30 mg of lansoprazole, 400 mg of metronidazole, and 250 mg ofclarithromycin, all taken twice a day for 7 days. The trial was funded by the Cancer ResearchCampaign (now part of Cancer Research United Kingdom) and the British United Provident
Association (BUPA) Foundation. Men aged 35–69 years and women aged 45–69 years wererandomized by week of attendance at a Well Person Screening Clinic conducted by BUPA.
All individuals had to be United Kingdom residents, registered with a National Health Service(NHS) general practitioner, so that their NHS records could be flagged and an automatic
notification sent to the study centre in the event of cancer registration or death.
Fig. 4.5.4 shows the expected numbers of people with gastric cancer in the trial according torandomized allocation (screened, or control), and among the screened group, the expected
numbers found to be negative and positive for H. pylori antibody. It also shows the expected
numbers of individuals with gastric cancer in the absence of treatment. Fig. 4.5.5 shows the
expected numbers with treatment assuming a 3-fold relative risk. Comparison of cases in thescreened and control groups would be the standard analysis, but a more powerful statisticalanalysis was specified in the protocol. As there is no expectation of an effect in H. pylorinegative people, one can ignore these and compare gastric cancer incidence in H. pyloripositive people in the two randomized arms (see Fig. 4.5.6). The standard nested case–control analysis compares 62 versus 85 cases of gastric cancer (Fig. 4.5.5), which would
yield a P value of borderline statistical significance (0.06). The more powerful statisticalanalysis (Fig. 4.5.6) compares 22 versus 45 cases, which yields a highly statisticallysignificant difference (P = 0.005).
In this trial, people were recruited from 10 United Kingdom screening centres between 1997
and 2006. They were randomly allocated, by week of attendance, at each screening centre,
to a screen-and-treat group or a control group. Since recruitment took place over a decade,the number of randomization groups is large, avoiding the loss of statistical power that canarise from cluster randomized trials. The nested case–control design, within the randomized
trial, provides an efficient approach, which is further enhanced by limiting the analysis toindividuals in the treated and control arms of the trial who develop gastric cancer and were
H. pylori-positive on the blood sample they provided at the time of randomization. Follow-up
will continue for a further 5 years or more to achieve the required statistical power necessary
for the trial results to be informative.

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Fig. 4.5.4. Helicobacter pylori Screening Study (HPSS): Study design and expected numbers ofgastric cancers in the absence of treatment.

Fig. 4.5.5. Helicobacter pylori Screening Study (HPSS): Study design and expected numbers ofgastric cancers with treatment.

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Fig. 4.5.6. Helicobacter pylori Screening Study (HPSS): Study design and expected numbers ofgastric cancers with treatment using statistical analysis, with enhanced power.

Acknowledgement
The author thanks Jonathan Bestwick for his statistical assistance in the preparation of thischapter.

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Disclosures of interests
Dr Francis Mégraud reports that his research unit at the University of Bordeaux received
grants from Aptalis Pharma; Dr Mégraud reports that his unit benefited from researchfunding from Danone Research and Biocodex; Dr Mégraud reports that he received support
for providing speeches from Aptalis Pharma and Meridian, and consultancy fees from Astra
Zeneca and Aptalis Pharma.
Dr Mārcis Leja reports that he currently benefits from Digestive Diseases Centre GASTRO
and Academic Histology Laboratory for the partnership with these institutions; Dr Leja
reports that his research group at the University of Latvia has benefitted from BIOHIT,EIKEN, and Vector-Best in the form of free reagent supply; Dr Leja reports that he received
personal speaker’s fees from Astra Zeneca, KRKA, and Nycomed.

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