ABSTRACT
Epidemiology is the study of the distribution and “determinants” of disease in human populations. In the context of cancer, this involves examination of differences in rates according to age, sex, race and place of residence, and how these might change over time and between countries or regions. It also entails “investigation” of various factors (such as smoking, diet or exposure to asbestos) which might increase or decrease the risk for cancer. Cancer is a collective term which embraces different malignant tumors which may be defined primarily by their site within the body (e.g. breast cancer) or solely by histological type (e.g. Kaposi’s sarcoma). Strategies for cancer control rely on knowledge of incidence and mortality rates for individual tumors as well as information on their specific risk factors. Only through epidemiological studies can definitive data be provided on the existence, extent and nature of cancer risks in humans and on the effectiveness of preventive and intervention strategies.
