The Measurement of Associations between Environmental Exposures and Cancer

The major strength of epidemiology is that its study subjects are human beings, the species to which we wish to generalize our results.Basic epidemiologic approaches are described here, with primary reference to cohort and case-control study designs.Various measures for assessing risk are distinguished: (a) relative risk, which is important for testing etiologic hypotheses, (b) attributable risk, which informs about excess disease burden in exposed compared to nonexposed individuals, and (c) population attributable risk, which is of value in estimating the proportion of disease in an entire community associated with a particular exposure.Strengths and shortcomings of epidemiologic methods and issues in the transmission of the results of epidemiologic studies to the public are discussed.The importance of influences beyond epidemiology on public perception of risk is stressed.