The role of epidemiological observation in elucidating the mechanisms of carcinogenesis.

Epidemiological observations concerning a number of carcinogenic agents have been used to make inferences about the biological mechanisms of carcinogenesis. These inferences have generally been based on comparisons of epidemiological data with the predictions of various mathematical models of the process of carcinogenesis. Particular interest has focused on the relationships between cancer occurrence and level of exposure, age at exposure and time since cessation of exposure, and the combined effect of two carcinogenic agents. Analyses of epidemiological data in relation to mathematical cancer models have led to conclusions about mechanisms of action, but the validity of these conclusions is necessarily limited by the nature of epidemiological data and the unverifiability of assumptions underlying the models. A more fruitful application of the epidemiological perspective in elucidating the mechanisms of carcinogenesis may be through collaborative studies involving the recently developed techniques of molecular biology and related areas.