United States General Accounting Office

GAO Report to the Chairman, Subcommittee

on Human Resources, Committee on

Government Reform and Oversight,

House of Representatives

March 1998 GULF WAR

VETERANS

Incidence of Tumors

Cannot Be Reliably

Determined From

Available Data

GAO/NSIAD-98-89

GAO United States

General Accounting Office

Washington, D.C. 20548

National Security and

International Affairs Division

B-278203 

March 3, 1998

The Honorable Christopher Shays

Chairman, Subcommittee on Human Resources

Committee on Government Reform and Oversight

House of Representatives

Dear Mr. Chairman:

Numerous claims of illnesses from Gulf War veterans and inconsistent

reports on veterans’ exposure to risk factors have prompted a number of

government studies on the nature, extent, and treatment of Gulf War

illnesses. In June of last year, we reported to you and other members of

Congress that government research efforts may not be able to provide

conclusive answers about the causes of veterans’ illnesses and that several

risk factors such as chemical and biological agents had been ruled out

prematurely as possible explanations for the reported illnesses. We also

reported that many veterans were unhappy with the quality of health care

treatments they had received from the Department of Veterans Affairs (VA)

and that enhanced monitoring is needed to determine if veterans are

getting any better or worse over time.1

In your letter to us on June 12, 1997, you raised concerns about whether

Gulf War veterans have an increased risk of developing certain cancers as

a result of their exposures to hazards in the Persian Gulf. You asked us to

examine pertinent data on the incidence of tumors among Gulf War

veterans and determine whether these data indicate any differences in

rates of tumors between Gulf War veterans and appropriate comparison

groups.2

 In this report, we assessed (1) the reliability of data sources

available for determining the incidence of tumors among Gulf War

veterans and (2) VA’s and the Department of Defense’s (DOD) use of data

sources to monitor tumors and other illnesses among Gulf War veterans.

The five types of data sources we reviewed were mortality data, medical

records, cancer registries, Gulf War veterans health registries, and survey

results.

1

Gulf War Illnesses: Improved Monitoring of Clinical Progress and Reexamination of Research

Emphasis Are Needed (GAO/NSIAD-97-163, June 23, 1997) and VA Health Care: Observations on

Medical Care Provided to Persian Gulf Veterans (GAO/T-HEHS-97-158, June 19, 1997).

2

Neoplasms, or tumors, involve the unrestricted growth of tissue in the body. They can be either

malignant (cancerous) or benign. Some benign tumors can also be life-threatening, such as brain

tumors. Incidence is defined as the number of new cases during a given period of time among those

exposed to the risk of developing the disease and is normally expressed as a rate.

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Although we sought to examine data sources that pertain directly to

tumors, many of the sources can also be used to assess other diseases that

may be associated with service in the Gulf War. Because of this, our

findings concerning the strengths and limitations of these data should be

relevant to the broader issue of monitoring other Gulf War illnesses as

well. In addition, it is important to point out that several of the data

sources we reviewed were not designed specifically for medical research

purposes but rather for other uses such as veteran outreach or the

administration of records.

Background Following Iraq’s invasion of Kuwait in August 1990, the United States and

other allied nations sent troops to the Persian Gulf region in Operation

Desert Shield. In the winter of 1991, the allied forces successfully attacked

Iraq in an air campaign and subsequent invasion by ground forces

(Operation Desert Storm). Approximately 700,000 American troops

participated in these actions. Although casualties were relatively light,

thousands of veterans have come forward complaining of various

illnesses, including cancer, in the years following the war.

During the Gulf War, American troops may have been exposed to several

known and potential health risks. These included chemical and biological

warfare agents, depleted uranium from munitions, smoke from oil-well

fires, infectious diseases, pesticides, petroleum fuels, and vaccines. Some

of these substances have been previously associated with different types

of cancer through animal laboratory studies and other epidemiological

research investigations. For example, combustion products from

petroleum include polyaromatic hydrocarbons, benzene, and carbon

disulfide, some of which are known to cause lung cancer when inhaled.

Exposure to certain pesticides has also been linked to lymphatic and lung

cancers. In addition, exposure to radioactive particles has been tied to

higher rates of respiratory and other cancers. Information on exposures

that took place during the Gulf War, however, has been either incomplete

or nonexistent due to the lack of record keeping and measurement before,

during, and after the deployment of troops; loss of key records; poor recall

by veterans; and other factors.

The development of cancer is usually characterized by a long latency

period of several years from an initial exposure to a harmful agent to a

definitive medical diagnosis. Depending on the nature and extent of the

exposure, type of cancer, and characteristics of different individuals, the

latency period may be as long as 30 years or more. The most common

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types of cancers have a latency period of 15 years or more, but in certain

situations cancer can develop more quickly. For example, when the

immune system is compromised, such as in cases of organ transplants,

certain types of cancer may appear within 1 year.

Given that there is a lengthy latency period for most tumors, it may be too

soon to detect any increase in tumors occurring among Gulf War veterans.3

 Also, since cancer is a relatively rare event,4 large population groups may

need to be observed over several years to assess incidence and determine

whether it has changed over time. Furthermore, without credible exposure

information, it is hard to form specific hypotheses about what kinds of

tumors might occur with what individuals. Although such constraints

exist, it is nonetheless important to begin monitoring and assessing

whether Gulf War veterans are suffering from an increase in tumors so

that appropriate health care and treatment can be provided where needed.

With many types of tumors, early detection is important to more effective

treatment outcomes.

Results in Brief None of the data sources that provide information on the health

characteristics of Gulf War veterans can be used to reliably estimate the

incidence of tumors. Existing federal and state data systems are generally

limited by poor coverage of the Gulf War veteran population and problems

of reporting accuracy and completeness. Following is a summary of our

assessment of each type of source:

• VA’s benefits information system can track the vital status and causes of

death of Gulf War veterans. However, not all cancers result in death, and

those that do may take several years to show up. As a result, the system

will underreport overall incidence.

• DOD and VA maintain large hospitalization reporting systems. However, a

large majority of Gulf War veterans (particularly those separated from the

service) do not use DOD and VA hospitals, and there has been little effort to

determine whether this hidden population has health conditions similar to

those of the population captured by the reporting systems. DOD’s reporting

3

In 1996, the Persian Gulf Veterans Coordinating Board concluded “the occurrence of some cancers

among Persian Gulf Veterans, although infrequent, has elevated concern over the possibility that these

cancers may be linked to service in the Persian Gulf.” The Board, though, also cited a 1994 Defense

Science Board report that pointed out that “because of the long latency period associated with cancer

originating from environmental causes, it is too early to evaluate cancer risk in Persian Gulf veterans.”

4

The average age-adjusted incidence rate for all types of cancer combined was 400 cases per 100,000

population in the United States in 1990-91 (National Cancer Institute, Cancer Rates and Risks 1996, 

p. 17). Among the age group that served in the Gulf War, incidence is lower (fewer than 100 cases per

100,000 population for the ages 15-44).

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system also does not account for outpatient medical care where more

diagnosis and treatment of many types of tumors have been occurring in

recent years. VA has recently begun to fill this gap for its outpatient

facilities, but it may take several years before consistent and reliable

reporting is available.

• A national cancer registry reports aggregate population rates and trends

but cannot be used to track the Gulf War population. Many available state

registries could be used to identify Gulf War veterans, but the registries

vary in terms of data quality and reporting consistency and coverage.

• DOD and VA health registries report information on the type of health

problems Gulf War veterans have experienced at the time of their

examination. However, because not all veterans are examined

(participation is on a self-selected basis), the information collected cannot

be used to estimate the frequency of illnesses among all Gulf War veterans.

• VA is conducting a national survey to study the general health status of

Gulf War veterans. The study uses representative samples of deployed and

nondeployed veterans. However, the response rate to the survey has been

low and the study’s sample size may be too small to assess any elevated

incidence of most cancers.

DOD and VA have initiated efforts to improve the utility of these data

systems but have not developed the capability to specifically address

questions about tumors or other illnesses among Gulf War veterans. As a

result, it is not known how many Gulf War veterans have tumors or

whether they have a higher incidence of them than other veterans. DOD and

VA have recently funded a few research studies that should provide

additional information on tumor cases in the future. However, these

studies are not the product of a systematic effort to study the incidence of

tumors, and limitations to the studies will prevent them from providing

reliable and valid estimates of tumors among Gulf War veterans.

According to agency officials, no other plans aside from periodic

assessments of mortality have been made to monitor tumor cases within

this population.

Mortality Data

VA Benefits Information

System

One source for estimating the incidence of cancer among Gulf War

veterans utilizes mortality as an indicator for incidence. VA maintains a

large administrative database containing records of claims for benefits

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B-278203 

made by veterans and their dependents.5 This database, the Beneficiary

Identification and Records Locator Subsystem (BIRLS), includes

information on more than 40 million individuals. Although not designed as

a research database, it does contain information on the vital status of

veterans and the location of veterans’ claim forms so that death

certificates can be retrieved to ascertain causes of death. VA pays death

benefits, including fixed payments for burial and funeral expenses, to

eligible survivors of deceased veterans. Dependents are required to submit

a copy of the veteran’s death certificate in order to receive these benefits.

The BIRLS datafile also contains the veteran’s name, social security number,

claim number, current address, and other benefits information. In

addition, the file includes a code that indicates whether the veteran was

deployed to the Gulf War.

VA and other researchers have estimated that death reporting in the BIRLS

database is relatively complete in terms of its coverage of the veteran

population.6

 Studies using large samples of known deaths have compared

vital status reporting in BIRLS with reporting in other national sources of

mortality data, such as the Master Beneficiary Record of the Social

Security Administration and the National Death Index, and found that

BIRLS covers 80 to 90 percent of the deceased veteran population. Another

strength of the BIRLS data is that they provide a relatively cost-effective

way to assess causes of death among veterans. Obtaining death

certificates directly from state health departments involves paying a fee of

several dollars for each certificate.

Using BIRLS or other mortality databases to assess overall cancer incidence

has several key limitations. First, mortality is a lagging indicator of

incidence. The latency period for most tumors can be more than 

10 years and the period of time until mortality is even longer. Second, in

general, mortality is an incomplete measure of cancer incidence because

cancer is not always fatal. Mortality data provide good estimates of

incidence for cancers that have a high mortality rate (such as lung and

liver cancers) but they are less useful for cancers with lower rates of

mortality (such as prostate and breast cancers). Because of these

5

Other databases containing records of deaths include the National Death Index, administered by the

National Center for Health Statistics, and the Social Security Administration’s Master Beneficiary

Record database. The National Death Index contains reports from the state offices that maintain death

certificates. The Master Beneficiary Record database contains a record of individuals whose benefits

were terminated because of death.

6

Page, W.F. et al, “Vital Status Ascertainment through the Files of the Department of Veterans Affairs

and the Social Security Administration” Annals of Epidemiology, vol. 6 (1996), pp. 102-109; Fisher, S.G.

et al, “Mortality Ascertainment in the Veterans Population: Alternatives to the National Death Index”

American Journal of Epidemiology, vol. 141 (1995), pp. 242-250.

Page 5 GAO/NSIAD-98-89 Gulf War Veterans
B-278203 

limitations, mortality data will systematically underreport overall cancer

incidence. In addition, by the time cases show up in the data, it may be too

late to help Gulf War veterans. Furthermore, while the reporting of

external causes of death, such as accidents, or broad disease categories,

such as coronary heart disease, is reasonably reliable, some

inconsistencies in cause of death reporting on death certificates have

occurred. Death certificates are less accurate in tracking difficult to

diagnose diseases, deaths involving multiple causes, and where there are

underlying causes of death that are not readily discernible.

Using VA’s Benefits

Information System to

Assess Tumors Among

Gulf War Veterans

VA in one published study used data from BIRLS to assess the mortality risk

from a range of diseases (including cancer) for all Persian Gulf veterans

compared with a sample of veterans who were not deployed to the Persian

Gulf.7

 The study covered deaths occurring in a 2-year period after the war

(May 1991 to September 1993). Death certificates for those veterans who

had been identified as having passed away were obtained from VA regional

offices and other locations and were reviewed for cause of death. The

study found that overall there was a small but significant excess of deaths

among Gulf War veterans (1,765 deaths) compared with nondeployed

veterans (1,729 deaths) and that the excess was due mainly to accidents

and not disease. Of the 1,765 Gulf War veterans who died during the study

period, 119 died from cancer, and there was no statistically significant

difference compared with the cancer death rate among nondeployed

veterans.

If a higher death rate from cancer was expected among Gulf War veterans

as a result of some exposure occurring during deployment, then they

would be unlikely to appear in this study given the short time period that

elapsed. VA is currently updating the study, extending the study period

through 1995, and the results should be published later this year. The

study’s authors identified another limitation (but it is not clear what effect

it had on the study’s findings)—specifically, whether the study’s

comparison groups were appropriately matched. Military personnel who

were ill or recovering from an illness would not have been deployed to the

Gulf War area. However, these personnel were included in the comparison

group of nondeployed veterans. This meant that the comparison group

may have been somewhat less healthy than the deployed veterans group.

The extent to which a higher rate of prior illnesses among nondeployed

veterans resulted in a different rate of mortality (or cancer mortality in

7

Kang, H.K., and Bullman, T.A., “Mortality Among U.S. Veterans of the Persian Gulf War,” New England

Journal of Medicine, vol. 335 (1996), pp. 1498-1504.

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particular) and thus biased the study findings is unknown. Finally, the use

of broad comparisons between deployed and nondeployed veterans rather

than more targeted comparisons of veterans based on specific types and

levels of exposures may also have affected the soundness of the study. A

comparison of deployed and nondeployed veterans has merit for

identifying potential widespread and severe health consequences.

However, defining the exposed population group as “all those who served

in the Gulf War” without regard to individual groups’ exposure histories

may obscure some service-connected illnesses. Efforts to exclude from

such studies portions of the deployed force who were at low risk of

exposure to harmful agents could lead to more meaningful results in such

comparative studies.

Medical Records

DOD’s and VA’s Automated

Hospitalization Reporting

Systems

DOD and VA each maintain an automated database containing medical and

demographic information on patients discharged from DOD and VA

hospitals. DOD’s system collects information from DOD military hospitals.

These hospitals are open to active duty personnel and, to a limited extent,

retired personnel. VA’s data system, the Patient Treatment File, covers all

VA hospitals. VA hospital care is generally available to veterans for

service-connected illnesses. Care is also provided on a discretionary basis

for nonservice-connected illnesses, depending on the availability of

facilities and resources and payment of a required co-payment by the

veteran. Veterans who may have been exposed to a toxic substance or

environmental hazard while serving in the Gulf War are included in a

designated category of veterans who have special eligibility for VA medical

care services. Both the DOD and VA data systems include medical discharge

diagnoses, which are coded according to standard ICD-9 (International

Classification of Diseases, 9th Revision) disease categories. In addition,

the data contain relevant information such as social security numbers,

date and place of birth, period of military service, length of hospital stay,

and surgical and other medical procedures conducted.

DOD’s and VA’s hospitalization data systems are large and contain millions

of records, but they do not represent the entire active duty and veteran

population. While DOD’s data include most hospitalizations of active duty

personnel, in large part because DOD medical care is free and readily

available to active duty personnel, there have been reports from some

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veterans’ groups of Gulf War veterans seeking medical care outside DOD.

According to these groups, veterans have done so to obtain specialized

care or because of concerns that the acknowledgment of their illnesses

within DOD could have a negative effect on their military careers. It is not

clear whether this would more often be the case for Gulf War veterans

with tumors than for nondeployed veterans.

VA also has an extensive network of medical centers across the country

but the overwhelming majority of veterans use other private and public

hospitals. A survey conducted by VA in the late 1980s, estimated that only

about 20 percent of veterans had ever used a VA hospital. With respect to

Gulf War veterans, it is not known whether there is greater or less use of

VA medical facilities. Since Gulf War veterans have been authorized special

eligibility for medical care, there may be greater use of VA medical centers

compared with some other groups of veterans. On the other hand, there

have been numerous accounts in the media and by veterans’ groups of

dissatisfaction with government efforts to address Gulf War veterans’

health problems. This may contribute to a greater reluctance among some

veterans to seek hospital care at VA medical facilities.

Another weakness of the hospitalization data systems has been the lack of

coverage of outpatient medical care. DOD currently has no centralized

reporting system for its outpatient facilities, although an automated

system is under development. Until recently, VA did not have an automated

system either. VA established an automated system in October 1996 to

begin collecting information on the use of its outpatient facilities and the

different types of medical care provided. Information is not available yet

on the accuracy and completeness of the reporting. Coverage of outpatient

facilities is important because there is a current trend in the health field

toward outpatient diagnosis and treatment of many types of tumors.

In addition to limitations in terms of population coverage, there are also

issues regarding the accuracy and completeness of hospitalization data

reporting. One strength of the reporting process is that standard disease

categories are coded so that comparable data can be collected from each

hospital and more specific types of diseases can be assessed. Furthermore,

the reporting allows for multiple discharge diagnoses to be recorded and

not just the principal cause for hospitalization. Miscoding of discharge

diagnoses, however, is a potential problem as shown by VA researchers in

previous assessments of certain types of cancer among Vietnam veterans.8

8

Kang, H.K. “Resources for Epidemiological Research in Vietnam Era Veteran Populations Within the

Department of Veterans Affairs” Epidemiology in Military and Veteran Populations (Washington, DC:

National Academy Press, 1991), pp. 97-103.

Page 8 GAO/NSIAD-98-89 Gulf War Veterans
B-278203 

In a case-control study, for example, of over 400 Vietnam veterans

identified in VA’s Patient Treatment File with a malignant tumor of

connective and other soft tissue, close to 40 percent of the records were

found to be miscoded or misclassified when hospital pathology reports

were subsequently collected and independently reviewed by an expert

pathologist.9

Using DOD’s and VA’s

Automated Hospitalization

Reporting Systems to

Assess Tumors Among

Gulf War Veterans

VA Tumors Analysis In May 1996, VA completed an analysis requested by your Subcommittee

that provided some information on the number of tumors among Gulf War

veterans compared with the number in a sample of nondeployed veterans.

The analysis sought to identify cases of tumors occurring immediately

after the war up through the early part of 1996. Existing VA databases,

including the Persian Gulf Health Registry, Patient Treatment File, and

BIRLS, were used as means to identify tumors. A breakdown by type of

tumor, age, gender, race, and branch of service was conducted after

merging the health registry and hospitalization data records; however,

these records were not subsequently merged with the benefits records

data (BIRLS) because the diagnostic coding used in the two systems is

different.10

As reported by VA, based only on the combined health registry and

hospitalization data, the number of individuals with diagnosed tumors was

relatively low but the number of Gulf War veterans was substantially

higher as compared with nondeployed veterans (1,691 out of 697,000 Gulf

War veterans compared with 1,092 out of 1,605,087 nondeployed veterans).

Most of the tumors identified, though, were benign and not malignant

cancers. Possible reasons for the higher rate according to VA are that

(1) priority eligibility status is given to Gulf War veterans for inpatient

treatment and (2) a special health registry exists for Gulf War veterans. In

contrast to these results, a larger number of diagnosed tumors was

9

Kang, H.K. et al, “Soft Tissue Sarcomas and Military Service in Vietnam: A Case Comparison Group

Analysis of Hospital Patients” Journal of Occupational Medicine, vol. 28 (1986), pp. 1215-1218.

10As discussed earlier, the VA hospitalization records data uses the standard ICD-9 coding

classification system. The coding of diagnoses in the benefits data is structured differently according

to parts of the anatomy.

Page 9 GAO/NSIAD-98-89 Gulf War Veterans
B-278203 

reported from the benefits records data (BIRLS) but the number of cases

among Gulf War veterans was lower compared with the number among

nondeployed veterans (6,397 out of 697,000 Gulf War veterans compared

with 21,227 out of 1,605,087 nondeployed veterans). Thus, the different VA

data sources present a different result for tumor cases in these population

groups.

VA has acknowledged that its analysis is quite limited because of

weaknesses in the existing data sources used. A key limitation is the poor

coverage the data provide of the veteran population.11 Veterans who use

non-VA medical care facilities are excluded. A potential source for

augmenting this is the use of the BIRLS data, which in addition to reporting

information on mortality claims reports information on medical disability

claims. Veterans, regardless of whether they receive medical treatment

from VA or elsewhere, can apply for disability claims. BIRLS tracks denied

and approved claims, including those for disabilities associated with

tumors. As a condition for qualifying for disability compensation, it must

be established that the disability is service-connected and that the

condition leading to the disability appeared either while the veteran was

on active duty or within a presumptive period after separation from the

service. For most cancers, however, the presumptive period is limited to 1

year. In principle, BIRLS includes other cases than those reported in the VA

hospital reporting system. The major restriction to using the data to

identify illnesses among Gulf War veterans, though, has been the difficulty

of merging the claims records with other VA hospitalization records

because of the different diagnostic coding systems used. The extent to

which a crosswalk could be developed to link the diagnostic codes has not

been determined.

Postwar Hospitalization

Experience Study

A large DOD-funded study was published last year examining the

hospitalization experience of all active duty Gulf War veterans compared

with a sample of other active duty military personnel who were not

deployed to the Gulf region.12 The purpose was to determine whether

participation in the Gulf War was associated with the occurrence of

serious illnesses requiring hospitalization. Using inpatient hospitalization

data records obtained from DOD, the study assessed hospitalizations

11Another potential weakness of the analysis is the use of large denominators (all deployed and

nondeployed personnel) for the comparison. As discussed earlier with respect to VA’s mortality study,

this may mask certain service-connected illnesses.

12Gray, G.C. et al, “The Postwar Hospitalization Experience of U.S. Veterans of the Persian Gulf War,”

New England Journal of Medicine, vol. 335 (1996) pp. 1505-13.

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B-278203 

occurring during the period August 1991 through September 1993. Overall,

the authors found there was no excess in hospitalizations among Gulf War

veterans compared with other military personnel. Among specific types of

hospitalizations, however, Gulf War veterans had higher rates in specific

years for tumors (in 1991), mental disorders (both 1992 and 1993),

diseases of the blood (in 1992), and diseases of the genitourinary system

(in 1991). For tumor cases reported in 1991, most involved benign

conditions and, although the rates were higher for Gulf War veterans, the

differences were not statistically different. The one exception, where a

significant difference (higher rate) was found, was for testicular cancer in

1991 hospitalizations. The investigators conducted a follow-on review of

hospitalizations for testicular cancer through March 1996 and found that

male Gulf War veterans who remained on active duty after the war were

not at increased risk of hospitalization for testicular cancer.

A major strength of this study is its large size and statistical power to

detect differences in rates of hospitalizations between deployed and

nondeployed military personnel. However, a key limitation of the study,

which influences the interpretation of the results, is that hospitalizations

of Gulf War veterans who separated from the service as well as any

hospitalizations of active duty personnel who used non-DOD hospitals are

excluded.13 The number of hospitalizations excluded from the study is not

known, but the number of veterans who separated from the service

increased substantially since the end of the war. According to DOD figures,

Gulf War veterans who remained on active duty declined to 66 percent in

1993 and to below 50 percent by 1995. Another important limitation of the

study is that the timeframe was far too short for detecting any diseases

resulting from possible exposures during the war, such as tumors, which

have lengthy latency periods. Extending the time period would address the

latency issue, but then the problem of missing hospitalizations would

increase as the number of Gulf War veterans remaining on active duty gets

smaller over time.

A related follow-up study is currently underway by the same researchers,

to examine hospitalizations of Gulf War veterans in military and

nonmilitary hospitals in the state of California. This study will merge

hospitalization data from three sources: DOD, VA, and the state government.

California maintains a database of patient hospital discharge information

collected from nonfederally licensed hospitals in the state (diagnoses are

coded using the ICD-9 classification system). The study will seek to

13In the Gulf War, 17 percent of the deployed forces were from National Guard or Reserve units. After

the war, these personnel returned to non-active duty status. Hospitalizations in this group would occur

at non-DOD hospitals.

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identify all Gulf War veterans who resided in the state at the time of or at

least a year prior to deployment. Internal Revenue Service files will be

matched with DOD’s roster of 697,000 Gulf War veterans to identify those

residing in the state (estimated to be about 12 percent of the Gulf War

force), and the resulting resident file will then be matched with the various

hospital data files to identify hospitalizations for each veteran. Although

the study results will probably not be generalizable to the entire Gulf War

population, the study is large and one of the first to systematically

combine military and nonmilitary hospitalizations. The study period is

longer (1991-95); however, the problem of detecting diseases with a

lengthy latency period is still an issue, and outpatient data will be

excluded. Currently, the study is in the initial data merging phase and is

not expected to be completed until 1998 or later.

Cancer Registries

National and State

Registries

Another source for estimating the incidence of cancer is the

population-based cancer registries along with other baseline demographic

data. Cancer registries are compilations of reports of cancer cases that are

filed by medical facilities (typically hospitals) on an ongoing basis

according to prescribed data coding procedures. Cancer registries can be

effective tools for determining incidence rates and for directing cancer

control efforts. Typically they are used to identify and monitor trends,

patterns, and variations in cancer incidence and mortality by geographic

location, ethnicity, gender, and age.

Cancer registries exist at the national, state, and local level. The national

cancer registry (the Surveillance, Epidemiology and End Results [SEER])

was established in 1973 by the National Cancer Institute. SEER collects data

from designated cancer registries that operate in various areas of the

country. Currently, it covers a group of five states and four metropolitan

areas that were selected for “their ability to operate and maintain a

population-based cancer reporting system and for their epidemiologically

significant population subgroups.”14 Most states also maintain cancer

registries. In 1992, Congress enacted the National Program of Cancer

Registries (P.L. 102-515), which authorized the Centers for Disease Control

and Prevention to fund states to improve existing cancer registries and

develop registries where they do not exist. In 1996, 41 funded states were

14Connecticut, Iowa, New Mexico, Utah, Hawaii, Detroit, San Francisco, Seattle-Puget Sound, and

Atlanta.

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B-278203 

collecting statewide cancer data. The Centers for Disease Control and

Prevention has set standards for reporting accuracy, timeliness, and

completeness. However, some differences exist across states in the level

and quality of reporting. Voluntary reporting is also encouraged from DOD

and VA hospitals. In addition to these registries, DOD administers its own

cancer registry (the Automated Central Tumor Registry) for active duty

troops and others (i.e., retirees and family members) who use DOD military

medical facilities. It was set up as a central registry in 1986 to compile,

track, and report cancer patient information from military medical

treatment facilities.

SEER is a comprehensive system for tracking cancer incidence for the

general population and key subgroups. In addition, provisions are made

for quality assurance checks on data reliability. However, in terms of its

suitability for assessing cancer rates in Gulf War veterans, SEER only

collects and reports aggregate information and does not include the

necessary individual-level identifiers that would be needed to distinguish

Gulf War veterans. SEER can provide incidence rates for the general

population and key population subgroups but not for the Gulf War veteran

population.

Many of the state registry systems generally do include individual

identifiers such as social security numbers, so a match against a roster of

Gulf War veterans, using common identifiers, could be conducted to

identify cancer cases within this group. Such a match of course would

need to address potential confidentiality issues involving the privacy of

cancer patient information. The accuracy, timeliness, and completeness of

reporting also varies by state registries. For example, many states only

require reporting by hospitals and do not capture cases diagnosed by

private physicians, laboratories, and health maintenance organizations.

Many of the registries also have different data field structures and are not

designed to be readily merged with other registries.

DOD’s central tumor registry contains over 188,000 records of current and

past cancer patients. While the reporting system is designed to capture all

cancer cases treated at DOD medical facilities, DOD officials have indicated

that complete reporting is not occurring. No systematic assessment has

been conducted to measure how complete the reporting is, and no quality

assurance system is in place to ensure that reporting is being done.

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Using Cancer Registries to

Assess Tumors Among

Gulf War Veterans

VA has provided initial funding to the Boston Environmental Hazards

Center to assess cancer incidence among Gulf War veterans in New

England. The Center previously examined cancer incidence among

Vietnam veterans and will employ a similar methodology for looking at

Gulf War veterans.15 The approach entails developing a roster of Gulf War

veterans and linking it (by identifying information such as names, dates of

birth, and social security numbers) with cancer cases that appear in the

state registries. The first phase of the study has been funded to create a

roster of Gulf War veterans in the New England area and develop a

framework for merging data together from the individual state registries.

The next phase of the study, to begin by 1999, will involve an assessment

of cancer incidence and mortality. The study design notes that it would not

be informative to analyze cancer incidence sooner because the time

interval between any exposures that may have occurred during the Gulf

War and the diagnosis of most cancers is “probably at least 10 years and

may extend as long as 20 to 40 years.” It is also intended that these health

outcomes be linked to information about potential environmental

exposure factors that may exist or become available from DOD military

records and other sources, including the location database being compiled

by the U.S. Army Center for Health Promotion and Preventive Medicine.

Although this study is several years away from completion, it appears to

provide a useful means for obtaining information about cancer incidence

in the future. Some of the strengths of the study are that it will use existing

data systems, identify and assess a large cohort of Gulf War veterans, and

can be readily updated over time. One key limitation of the study,

however, is that the results will not be generalizable to the entire Gulf War

population since only the New England states will be included. Also, it is

not known whether there is complete reporting of cases to the registries,

particularly with respect to cases diagnosed outside of the hospital setting

and cases from border areas that may get reported in other state registries

outside the New England area.

Gulf War Veteran

Health Registries

Both DOD and VA have established separate programs that provide medical

examinations and diagnostic services, free of charge, to Gulf War veterans.

VA began its Persian Gulf Health Registry Examination Program in 1992,

and DOD started its Comprehensive Clinical Evaluation Program in 1994.

The programs are open to all active duty, separated, and retired military

personnel who were veterans of the Persian Gulf deployment. An existing

15Clapp, R.W. et al, “Cancer Surveillance of Veterans in Massachusetts, USA, 1982-1988,” International

Journal of Epidemiology, vol. 20 (1991), pp 7-12.

Page 14 GAO/NSIAD-98-89 Gulf War Veterans
B-278203 

health problem is not necessary for participation in the programs; any Gulf

War veteran with health questions or concerns is eligible to enroll on a

voluntary basis. Currently, the programs are designed to follow a standard

protocol that requires registry physicians to obtain a detailed medical

history, conduct a physical examination, and order basic laboratory tests.

Further diagnostic procedures and referral to specialized medical centers

are available for veterans with health problems that cannot be

satisfactorily diagnosed from the initial evaluation. As of April 1997,

approximately 66,000 veterans completed VA’s registry examination, and

over 31,000 veterans completed DOD’s examination.

While the registry programs are primarily intended to provide diagnostic

services and treatment to Gulf War veterans, the programs also gather and

report data on the nature of the veterans’ health problems and the types of

risk factors veterans may have been exposed to in the Gulf War. The most

common symptoms reported among veterans examined include fatigue,

skin rashes, muscle and joint pain, headaches, and memory loss.

Approximately 80 percent of the veterans with symptoms have been

diagnosed with one or more recognizable diseases; however, the other

20 percent with symptoms remain undiagnosed. Diseases involving

musculoskeletal and connective tissue, psychological conditions, and the

respiratory system were diagnosed most frequently. The number of

registry veterans with a primary diagnosis of a malignant or benign tumor

is very small, less than 1 percent.

The suitability of the registries for assessing cancer incidence is extremely

limited. As designed, the registries are not intended to be used to

determine the frequency and causes of illnesses among the general Gulf

War veteran population. A principal reason for this is that the participants

volunteered for their examinations and were not selected based on a

random sample (selection bias). Therefore, there is no way to know

whether the health problems found among the registry participants are

similar to those of the general population of Gulf War veterans. In

addition, because there is no ready comparison or control group for the

registry participants, there is no means to interpret the significance of the

data that are reported. A further limitation of the registry data is that they

capture information about the health of veterans only at one point in time.

Thus, if a veteran develops cancer or another illness later on, the registry

data will not reflect this.

Data quality concerns also have been raised in a previous review of the VA

registry by the Institute of Medicine. The Institute found, for example, that

Page 15 GAO/NSIAD-98-89 Gulf War Veterans
B-278203 

there was a considerable delay between the collection of the examination

data and their entry into the registry database.16 In other ongoing work we

are conducting on the quality of health care Gulf War veterans are

receiving, we also found that VA medical facilities have not reported

registry examination information consistently. It appears that a large

number of case records submitted for input into the registry database have

been rejected and sent back to the medical facilities due to coding errors.

At the same time, effective quality assurance procedures have not been in

place to ensure that rejected records are corrected and reentered into the

database. Thus, data coverage even for those who participated in the

registries has been incomplete.

Survey Data Another data approach involves developing information about incidence

by using survey methods, such as administering a questionnaire to a

sample of veterans. As opposed to the other approaches, which employ

data from databases administered by federal or state agencies, the

researcher has more control over the data that are being gathered.

Specifically, the researcher could ensure that the data are representative

of the overall population of Gulf War veterans.

Significant advantages to using the survey approach include the ability to

draw a random sample of Gulf War veterans and a comparison group 

(e.g., veterans who had not deployed to the Gulf War region). A survey

also permits the researcher to gather other information, such as

information about exposures and family history, that might shed light on

the etiology of disease.

Limitations with this approach include the possibility of response bias

(individuals who complete the survey not being representative of the

sample as a whole) and the subjectivity of self-assessments. There are

standard ways of dealing with these limitations. The problem of response

bias can be dealt with first by sending out multiple questionnaires. The

extent to which response bias is a factor can be estimated through a

special survey of nonrespondents, which is typically conducted by

telephone. The results of the nonrespondent survey are compared against

the results of the principal survey to gauge the degree to which

respondents are typical of the overall sample. Subjectivity of the

assessments of cancer can also be gauged to a degree through an

independent medical review of a subsample of respondents. In addition,

16Institute of Medicine Health Consequences of Service During the Persian Gulf War: Initial Findings

and Recommendations for Immediate Action 1995.

Page 16 GAO/NSIAD-98-89 Gulf War Veterans
B-278203 

subjectivity of assessments is somewhat less of a concern in terms of

tumors than many other illnesses.

Also, care needs to be taken to ensure that the size of the sample is large

enough to characterize with confidence differences between the Gulf War

veteran and the comparison groups. Tumors that have a low background

incidence would need to be studied with extremely large sample sizes to

detect an elevated incidence among Gulf War veterans. Sample sizes

required to draw conclusions would need to be determined at the earliest

stages of the study.

A further concern in implementing large population surveys is that they

tend to be much more costly than the other approaches being presented

here. In addition, the type and number of questions must be restricted or

people will not respond.

VA National Survey This approach is being employed by VA to study the general health status

of Gulf War veterans. The National Health Survey of Persian Gulf War Era

Veterans uses a mailed survey to compare self-reported symptoms and

illnesses between a random sample of 15,000 Gulf War and 15,000

nondeployed veterans. The questionnaire includes a checklist of illnesses,

including skin cancer and “any other cancer” and a checklist of symptoms

such as “coughing” and “skin rashes.” In addition to questions about

current health status, respondents are also asked to report about their

exposure to a list of agents including nerve gas, depleted uranium, and

smoke from oil well fires while they were in the Gulf War region.

The overall response rate to the survey has been relatively low

(57 percent). VA is conducting a survey of nonrespondents in order to

evaluate nonresponse bias. VA is also addressing the limitation imposed by

subjective assessments through an independent review of medical records

and “comprehensive physical examination” of a subsample of 2,000

respondents (1,000 in each of the Gulf War veteran and nondeployed

veterans groups).

The sample size of VA’s survey may also be too small to identify elevated

incidence of most cancers. With respect to the issue of statistical power,

VA has acknowledged that, “the study may provide inadequate statistical

power to detect a small increase in risk for rare adverse health outcomes

in a particular subgroup of veterans.”

Page 17 GAO/NSIAD-98-89 Gulf War Veterans
B-278203 

In 1996, the Institute of Medicine concluded, “This is a well-designed and

well-intended study.” According to the Institute, however, “there appeared

to be little statistical input in the analysis plan reviewed, and these data

will require sophisticated statistical adjustment.”

Iowa State Survey A population-based survey to assess the prevalence of self-reported

symptoms and illnesses among Gulf War veterans was also conducted in

Iowa.17 The study used a telephone interview approach to survey a random

sample of Gulf War and non-Gulf War veterans from Iowa. Approximately

3,700 veterans were interviewed during the period September 1995

through May 1996. Overall, the study found that Gulf War veterans

reported a significantly higher prevalence of a wide range of medical and

psychiatric conditions compared with military personnel who were not

deployed to the Gulf War. The primary conditions where differences were

reported include depression, posttraumatic stress syndrome, chronic

fatigue, cognitive dysfunction, and respiratory diseases. The rate of cancer

reported among these Gulf War veterans was generally low (an estimated

rate of about 1 per 100 subjects), but it was slightly higher than that of the

comparison group.

Conclusions and

Recommendation

No direct link has been established between potential exposures that

occurred during the Gulf War and the development of tumors among

veterans. However, concerns have been raised because many of the

exposure agents in question have previously been associated with certain

cancers. This has led to interest in determining if the cancer incidence rate

among Gulf War veterans is higher than the rates within other appropriate

comparison groups. If there is a higher incidence that identifies an

emerging health problem, then outreach efforts could be conducted to

target appropriate diagnosis and treatment to those potentially at risk.

Due to the long latency period of most tumors, it may be too soon to

detect whether there is an increased incidence of tumors among Gulf War

veterans. Nonetheless, it may be important to collect information now and

begin planning for monitoring the future health status of veterans.

However, the existing data sources and research applications we

reviewed, provide very limited information about the incidence of tumors

or other illnesses among Gulf War veterans. Federal research studies that

17The Iowa Persian Gulf Study Group, “Self-Reported Illness and Health Status Among Gulf War

Veterans,” Journal of the American Medical Association, 277 (1997), 238-245. This study was supported

by the Iowa Department of Public Health, University of Iowa, and the National Center for

Environmental Health, Centers for Disease Control and Prevention, Atlanta.

Page 18 GAO/NSIAD-98-89 Gulf War Veterans
B-278203 

are currently underway to assess tumors should help fill the gap, but these

studies are limited in terms of their coverage of the Gulf War veteran

population, data quality, and timeliness. Thus, it will also be difficult to

determine whether Gulf War veterans have a higher incidence of tumors

than other veterans in the future.

In our June report of last year,18 we found that DOD and VA had no effective

means to determine whether ill Gulf War veterans were getting better or

worse over time and recommended that DOD and VA develop a plan to

monitor their medical progress. This recommendation was effectively

incorporated into the recently enacted National Defense Authorization Act

for Fiscal Year 1998, as part of a broader initiative requiring the

Secretaries of Defense and Veterans Affairs to monitor health care

services and treatment to Gulf War veterans.19 In response to this, DOD and

VA have asked the Institute of Medicine to establish a committee of experts

to assess the appropriate methodology for monitoring health outcomes.

However, the ability to monitor veterans’ health conditions may be

seriously handicapped by the data constraints we have noted in this

report.

In order to evaluate more effectively the incidence of tumors and other

Gulf War illnesses over time, we recommend that the Secretaries of

Defense and Veterans Affairs continue to strengthen existing monitoring

capabilities. Attention should be directed toward improving the utility of

existing data systems and particularly in developing cost-effective ways to

make data systems more compatible with one another so that information

from different sources can be linked. In addition, steps should be taken to

address the data quality concerns we identified in this report. While we

believe such improvements can lead to more effective monitoring

capabilities, the existing data systems may be insufficient to answer the

question about cancer incidence or other illnesses among Gulf War

veterans. Therefore, further research efforts will be needed to supplement

the available data systems. For example, little is known about the health

status of veterans who receive medical care from sources other than DOD

and VA facilities. Practical approaches should be developed to determine

whether there may be emerging health problems among these veterans.

18Gulf War Illnesses: Improved Monitoring of Clinical Progress and Reexamination of Research

Emphasis Are Needed (GAO/NSIAD-97-163, June 23, 1997).

19Section 762 of Public Law 105-85, November 18, 1997. In addition, the House Appropriations

Committee, in its report on the Department of Veterans Affairs Appropriations for Fiscal Year 1998,

recommended that DOD and VA develop and implement a plan for monitoring the health of Gulf War

veterans (H.R. Rep. No. 105-175 at pages 15-16, 1997).

Page 19 GAO/NSIAD-98-89 Gulf War Veterans
B-278203 

Agency Comments

and Our Evaluation

DOD provided written comments on a draft of this report (see app. I), and

VA provided oral comments. Generally, DOD and VA concurred with our

overall findings regarding the inadequacies of existing data systems for

assessing tumors among Gulf War veterans and our recommendations to

improve monitoring capabilities. They emphasized that our

recommendations support initiatives they currently have underway to

strengthen health information reporting systems and the transfer of data

between the two agencies. According to DOD, these actions are part of a

long-term effort it is working on to develop a comprehensive system for

maintaining medical records of all illnesses and injuries that military

personnel may suffer, the care they receive, and their exposure to different

hazards. DOD noted a key objective of this work is to apply lessons learned

from the Gulf War experience to improve necessary medical surveillance

and record keeping for future military deployments. While we recognize

that DOD’s efforts will likely improve the utility of these data systems to

some extent, we are concerned that they will continue to be insufficient to

assess Gulf War illnesses such as tumors.

DOD and VA were concerned about references in the report to illnesses

other than cancer. They noted the report does a good job in highlighting

the strengths and weaknesses of the data sources available for assessing

the incidence of tumors among Gulf War veterans, but that it does not

include a comparable review of other non-cancer health information

systems or research studies that may exist. We modified the report title

and some language to clarify the scope of our work, where appropriate.

However, we continue to believe that our findings regarding the key data

sources discussed in this report, with the exception of the cancer registry

reporting systems, are applicable to assessing other illnesses that may be

associated with Gulf War veterans. For example, the lack of outpatient

data affects the reporting of many types of illnesses, not just tumors.

Although there are other research studies underway to investigate

different symptoms and illnesses in the Gulf War veteran population, we

are unaware of any other government data reporting systems that provide

a means to assess illnesses in this population.

VA officials also questioned statements we made in the report highlighting

the importance of collecting baseline information on tumor incidence

among Gulf War veterans at this time. They believe that available research

information, which has shown a lack of any increase in cancer mortality or

hospitalization rates among Gulf War veterans, does not support investing

in further monitoring, given other Gulf War research priorities. VA

contends that the usefulness of such baseline information is negligible for

Page 20 GAO/NSIAD-98-89 Gulf War Veterans
B-278203 

future research efforts because any future rates of tumors would need to

be compared with military and general population controls from the same

time period. While we agree that such comparisons are important, the

existing research information on tumor incidence in the Gulf War

population is quite limited and, therefore, cannot be used as a basis to say

there is no increased rate in tumor cases. Tracking incidence over time is

also important in order to assess whether the number of new cases is

occurring at a similar or different rate than a comparison group of

veterans.

DOD also made the point that establishing a national cancer registry with

standardized reporting of cancers across the nation, would address many

of the data problems noted in our report and be of use in assessing

military and nonmilitary populations. A recommendation for establishing

such a reporting system was beyond the scope of our work.

DOD and VA also provided technical comments, which we incorporated

where appropriate.

Scope and

Methodology

The focus of our work was to identify and assess available data sources

and federal research initiatives to estimate the incidence of tumors among

Gulf War veterans. To address these objectives, we reviewed relevant

literature and agency documents and collected information directly from

agency officials and selected outside experts. We identified and reviewed

available literature on a variety of topics including Gulf War illnesses,

cancer epidemiology, and other uses of federal and state medical

information systems (e.g., studies of cancer rates among Vietnam veterans

potentially exposed to Agent Orange). We also interviewed officials from

DOD, VA, the National Cancer Institute, and the Medical Followup Agency of

the Institute of Medicine. Through these interviews and materials

collected, we learned about the availability of data, their strengths and

limitations, and their applications for monitoring the incidence of tumors

and other illnesses. We also discussed past and ongoing research efforts to

assess the magnitude and frequency Gulf War illnesses with agency

officials.

An important limitation of our study is that we did not obtain the

databases and independently assess their reliability and validity. We did

not, for example, assess data entry procedures to verify the accuracy and

completeness of reporting. Furthermore, we did not evaluate the

effectiveness of database quality assurance practices.

Page 21 GAO/NSIAD-98-89 Gulf War Veterans
B-278203 

We conducted our review between July and December 1997 in accordance

with generally accepted government auditing standards.

As agreed with your office, unless you publicly announce its contents

earlier, we plan no further distribution of this report until 30 days from its

issue date. At that time, we will send copies of this report to other

interested congressional committees, the Secretaries of Defense and

Veterans Affairs, and other interested parties. We will also make copies

available to others upon request.

If you or your staff have any questions or would like additional

information, please contact me at (202) 512-3092. Major contributors to

this report were John Oppenheim, Dan Engelberg, and Lê Xuân Hy.

Sincerely yours,

Kwai-Cheung Chan

Director, Special Studies and Evaluations

Page 22 GAO/NSIAD-98-89 Gulf War Veterans
Page 23 GAO/NSIAD-98-89 Gulf War Veterans
Appendix I 

Comments From the Department of Defense

Page 24 GAO/NSIAD-98-89 Gulf War Veterans
Appendix I 

Comments From the Department of Defense

Now on p. 19.

Page 25 GAO/NSIAD-98-89 Gulf War Veterans
Appendix I 

Comments From the Department of Defense

(713007) Page 26 GAO/NSIAD-98-89 Gulf War Veterans
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