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Epidemiology 242: Cancer Epidemiology. Zuo-Feng Zhang, MD, PhD Fall Quarter, 2009. Overall Objectives of the Course.
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Epidemiology 242: Cancer Epidemiology Zuo-Feng Zhang, MD, PhD Fall Quarter, 2009
Overall Objectives of the Course • The overall objectives are to introduce basic concept in cancer epidemiology, including concepts of carcinogenesis, multistage models, pre-malignant lesion, international patterns of cancer.
Overall Objectives of the Course • To discuss major etiologic issues for a variety of cancers including smoking, alcohol drinking, virus, radiation, nutrition, occupational and environmental exposures. • To review epidemiological data on major cancers including prostate, breast, lung, and other cancers. • To lecture on the basic concepts of molecular and genetic epidemiology.
Introduction to Cancer Epidemiology • (1) To overview the cancer magnitude • (2) To familiarize students with basic concepts of tumor and its classification • (3) To introduce basic concept of carcinogenesis and cancer epidemiology
Why Cancer is a Major Public Health Problem? • Improved medical care and public health have lead to: • Decrease and control of common diseases of childhood and infectious disease, the major causes of death in the past • the increase of life expectation • the increase of the proportion of aging population, since cancer is generally considered as an aging disease, cancer becomes a major public health problem.
Number of deaths for leading causes of death • Heart disease: 631,636 • Cancer: 559,888 • Stroke (cerebrovascular diseases): 137,119 • Chronic lower respiratory diseases: 124,583 • Accidents (unintentional injuries): 121,599 • Diabetes: 72,449 • Alzheimer's disease: 72,432 • Influenza and Pneumonia: 56,326 • Nephritis, nephrotic syndrome, and nephrosis: 45,344 • Septicemia: 34,234
Incidence by sex and cancer site, World 2002 Source: Table 1: Parkin DM, et al. CA Cancer J Clin [2005]; 55: 74-108
Mortality by sex and cancer site, World Source: Table 1: Parkin DM, et al. CA Cancer J Clin [2005]; 55: 74-108
The Major Cancers • Lung (ICD-10 C33 and C34) • Breast (female, C50) • Colon/rectum (C18-C20) • Stomach (C16) • Prostate (C61) • Liver (C22) • Cervix uteri (C53) • Esophagus (C15)
Definition • Cancer epidemiology is the study of the pattern of cancer in populations. • Its essential aim is to identify causes of cancer, including preventable (avoidable) causes and inherited tumor susceptibility. • It is also play an critical role in many other areas of cancer research including evaluation of screening effects, cancer prevention and control • Current studies directions includes molecular and genetic epidemiology of cancer.
Types of Epidemiologic Studies • Descriptive Epidemiologic study: To describe the difference in occurrence of a particular cancer between different groups (age, gender, race, country, a period of time for time trend) and to generate the hypothesis for increased/decreased for the specific tumor type.
Types of Epidemiological Studies • Analytic Epidemiology: To study risk factors or potential causes of cancer by a particular study design, e.g., case-control study or cohort study.
Types of Epidemiological Studies • Intervention studies: Applying the knowledge (risk/protective factors) obtained from analytic epidemiological studies to specific population in order to reduce the risk of cancer.
Percentage of Cancer Deaths Attributed to Various Factors (Doll R and Peto R, JNCI, 1981) • Tobacco Use: 30% (25%-40%) • Diet:35% (10%-70%) • Infection: 10%? (1%-?) • Reproductive & Sexual Behavior: 7% (1%-13%) • Occupation: 4% (<2%-8%) • Alcohol: 3% (2%-4%) • Geophysical factors (natural radiation): 3% (2-4%) • Pollution: 2% (<1% – 5%) • Food additive: <1% (-5% – 2%) • Medicines and Medical Procedures: 1% (0.5%-3%) • Industrial consumer products <1% (<1%-2%) • Unknown: ?, ?
Harvard Center for Cancer Prevention (www.hsph.harvard.edu/cancer) • Tobacco: 30% • Diet in adult life, including obesity: 30% • Sedentary lifestyle: 5% • Infectious agents: 5% • Defects in single genes that run in family: 5-10%
Lichtenstein P, Holm NV, Verkasalo PK, Iliadou A, Kaprio J, Koskenvuo M, Pukkala E, Skytthe A, Hemminki K. NEJM, 2000
Chemical/environmental carcinogens • Smoking and lung cancer • Sun exposure and squamous cell carcinoma of skin • Asbestos exposure and lung cancer • Smoke food risk with nitrosamines and adenocarcinoma of the stomach • Alcohol drinking and squamous cell carcinoma of esophagus • Aflatoxin B1 and liver cancer
Radiation • Exposure to ultraviolet radiation (in the form of sunlight) and squamous cell carcinoma of skin • Ionizing radiation is related to skin cancer and leukemia in radiologist
Viral factors • HPV (human papilloma virus) and Cervix cancer • EBV(Epstein-Barr virus) and Nasopharyngeal cancer, Burkitt’s lymphoma • HBV (hepatitis B virus) and hepatocellular carcinoma • HIV (human immunodeficiency virus) and Kaposi’s sarcoma
http://www.yourdiseaserisk.wustl.edu/hccpquiz.pl?lang=english&func=home&page=cancer_indexhttp://www.yourdiseaserisk.wustl.edu/hccpquiz.pl?lang=english&func=home&page=cancer_index