Anita Kumar and Victoria Blinder
Cancer Epidemiology Research Methods
• Epidemiology: Study of distribution, determinants, & outcomes of cancer at a population level; applies public health or policy perspective, rather than the perspective of an individual pt
• “Efficacy”: Treatment demonstrates an effect, often in a clinical trial, vs. “effectiveness”: Effect in “real-world,” at the population level
• Observational studies: Cross-sectional, cohort, & case-control
• Experimental studies: Individual-based vs. community-based
• Epidemiology research can include analyses of patterns of care, comparative outcomes, cost-effectiveness, & health care disparities.
• A classic study showed women w/breast cancer who are uninsured or on Medicaid had a higher risk of death compared to women w/private insurance (NEJM 1993;329:326).
• Molecular & genetic epidemiology: Identification of biomarkers & genetic features linked to cancer susceptibility
Cancer Cases and Deaths
U.S. cancer incidence trends 1998–2008 (ACS Cancer Facts & Figures 2012):
• Cancer is a disease of older individuals, incidence ↑ w/aging population
• ↓ in lung cancer due to decline in smoking
• ↓ in colorectal, cervical cancer w/early detection, screening
• ↓ in stomach cancer due to ↓ in H. pylori infection
• ↓ in prostate cancer incidence due to ↓ in PSA screening
• Stable breast cancer incidence (period of decline in 2002–2003 due to ↓ in HRT use)
• ↑ incidence of HPV-related oropharyngeal cancer, esophageal adenocarcinoma, liver & intrahepatic bile duct, pancreas, thyroid, melanoma of skin, & kidney cancer
Figure 1-1
Global Cancer Epidemiology
• Temporal trends: (1) Cancer incidence is ↑ in the developing world due to ↑ longevity, & growing adoption of Western diet, physical inactivity, & tobacco use; (2) ↓ incidence of cancers due to infectious etiologies (stomach, liver, uterine cervix)
• Environmental factors that contribute to geographic distribution of cancer, eg, stomach cancer incidence rates highest in Eastern Asia & Central/Eastern Europe due to chronic H. pylori infection & diets high in salt & processed foods, low in fresh fruits & vegetables
• Migration studies: Japanese migrants to California have lower rates of gastric cancer compared to country of origin, but higher than California residents (Cancer 1965;18:656)
Etiologic Agents in Cancer