Sandbox:Cancer screening and primary care

# Overview
Worldwide, cancer is among the leading causes of morbidity and mortality; cancer contributed to approximately 8.2 million deaths in 2012, or an estimated 13% of overall deaths. WHO expects a 70% increase in the number of new cancer cases over the next two decades. The burden of cancer is substantial and increasing worldwide. The incidence, prevalence, and mortality of specific cancers vary widely across countries as a result of variations in  lifestyle risk factors (such as tobacco use, physical inactivity, excess body weight, reproductive patterns), the prevalence of carcinogenic infections (e.g., Hepatitis B, Hepatitis C, HPV), genetics, and the availability of health care resources. In 2012, lung, prostate, colorectal, gastric, and liver carcinomas were the most common cancers among men, while breast, colorectal, lung, cervical, and gastric carcinomas were most common among women. In 2014, the Agency for Healthcare Research and Quality estimated the direct medical costs associated with cancer in United States at $87.7 billion dollars. It is estimated that HBV/HCV and HPV are responsible for up to 20% of cancer deaths in low- and middle-income countries. It is also estimated that more than 30% of these cases are preventable. Measures to prevent some types of cancer include effective screening, vaccination, and lifestyle modifications. This page provides information about the epidemiology and primary care aspects of preventing cancer.

# Epidemiology
Worldwide, cancer is among the leading causes of morbidity and mortality; cancer contributed to approximately 8.2 million deaths in 2012, or an estimated 13% of overall deaths. The most common type of cancer (excluding non-melanoma skin cancers) is breast cancer; it is estimated that there were more than 249,000 new cases in the United States in 2016. The next most common cancers are lung cancer and prostate cancer. In the United States, to qualify as a common cancer, the estimated annual incidence for 2016 had to be 40,000 cases or more.
The following table presents official estimates of new cases and deaths in the United States for each common cancer type:

## Adulthood Cancers
- Rates are per 100,000 persons and are age-adjusted to the 2000 U.S. standard population.
- Rates are per 100,000 persons and are age-adjusted to the 2000 U.S. standard population.

## Childhood Cancers
In 2013, the most commonly diagnosed cancers and leading causes of cancer-related death in children aged 0 to 19 years were leukemia and central nervous system cancers.
- Rates are per 100,000 persons and are age-adjusted to the 2000 U.S. standard population.
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# Prevention
Effective measures for cancer prevention include:
- Screening
- Vaccination
- Lifestyle modifications

# Screening

## Breast Cancer

### Relevance of Breast Cancer Screening
Studies have reported that, for women of all age groups with an average risk, breast cancer screening was associated with a reduction in breast cancer mortality of approximately 20%, although there was an uncertainty in the quantitative estimates of outcomes for different breast cancer screening strategies in the United States.
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## Colon Cancer
Relevance of Colon Cancer Screenings
Studies have reported a 40% to 60% risk reduction for the incidence o colorectal cancer and mortality from colorectal cancer after screening colonoscopy.
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## Cervical Cancer
Relevance of Cervical Cancer Screening
Studies have shown that, in patients undergoing regular cervical cancer screenings, approximately 70%-80% of cervical cancer deaths can be prevented.
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## Lung Cancer
Lung caner screening relevance
The National Lung Screen Trial (NLST), a randomized controlled trial, involving 50,000 participants as demonstrated a 20% relative lung cancer mortality benefit.
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# Vaccination
Relevance of the HPV Vaccine in Cancer Prevention
Studies have reported that the development of the 4vHPV vaccine has decreased the prevalence of HPV 6/11/16/18 cervical/vaginal infections, genital warts, low- and high-grade cytological abnormalities, CIN2, CIN3, and AIS among females in their teens and 20s.
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Relevance of the Hepatits B Vaccine in Cancer Prevention
Strong evidence that hepatocellular cancer (HCC) can be prevented is provided by a cluster randomized controlled trial of the immunization of 75,000 newborns with hepatitis B virus (HBV) vaccine. After a median of about 25 years of follow-up, the incidence ratio of primary liver cancer in the vaccination-at-birth group versus the control group (68% of whom received catch-up vaccinations at ages 1014 years) was 0.16 (95% confidence interval, 0.030.77). These findings suggest that if HBV can be prevented, then much HCC can be prevented.
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# Lifestyle modifications
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