Epidemiology of neoplasms

1. Concept

Cancer epidemiology studies the distribution and determinants of neoplasms, providing major clues about cancer causation. Cancer is among the leading global causes of death (alongside infectious and cardiovascular disease).

2. Distribution by sex

	Men (incidence → mortality)	Women (incidence → mortality)
1st	Prostate (incidence) / Lung (mortality)	Breast (incidence) / Lung (mortality)
2nd	Lung / Prostate	Lung / Breast
3rd	Colon / Colon	Colon / Colon

• Lung = leading cancer killer (smoking-related). Prostate/breast — high incidence but better survival (screening, targeted therapy). Stomach & colorectal mortality declining (food preservation; dietary changes).

3. Determinants

• Geography/environment — diet, habits, infections: stomach cancer ~7× higher in Japan; breast cancer higher in US/Europe; HCC high in developing/African populations.
• Environmental carcinogens — smoking (lung, throat), alcohol (oral, esophagus, breast, liver), radiation, smoked meats (stomach), obesity/inactivity (colon, breast, endometrium); occupational: arsenic (lung/skin), benzene (leukemia), cadmium (prostate).
• Age — incidence rises with age (somatic mutation accumulation); most deaths age 55–75. Childhood: leukemias, CNS tumors, sarcomas.
• Heredity — AD (retinoblastoma, Li-Fraumeni, FAP, melanoma), AR (xeroderma pigmentosum, ataxia-telangiectasia), familial clustering (breast, ovarian, pancreatic).

4. Screening & prevention principles

• Tests defined by sensitivity/specificity; positive predictive value depends on disease prevalence.
• Primary prevention (risk reduction, vaccines), secondary (screening for early/premalignant disease), tertiary (reduce recurrence).

💡 High-yield: Lung = top cancer killer (both sexes); prostate (M) / breast (F) most common by incidence. Geography reflects environment (stomach↑ Japan, HCC↑ Africa). Risk: smoking, alcohol, obesity, infection, age, heredity. PPV depends on prevalence; prevention = primary/secondary/tertiary.