Descriptive and analytic epidemiology. Bridges to cancer control

Epidemiology serves as a bridge between basic science and cancer control. The two major orientations of epidemiology are descriptive and analytic. The former is useful in assessing the scope and dimensions of the cancer problem and the latter is used to assess environmental and lifestyle sources of cancer risk. A recent development in descriptive epidemiology is the use of functional measures of disease such as lost life expectancy. In analytical epidemiology, there is new or renewed interest in several lifestyle factors including diet and exercise as well as environmental factors such as involuntary tobacco exposure and radon in dwellings. Review of the evidence should consider the strengths and weaknesses of different research procedures. Each method is inconclusive by itself but, the different research designs of epidemiology collectively may represent a hierarchy of proof. Although the roles of many factors remain to be defined, the aggregate epidemiologic data continue to demonstrate the special importance of personal behavior and lifestyle in affecting cancer risk.