Epidemiological data and multistage carcinogenesis

The purpose of this review has been to demonstrate that a wide range of epidemiological phenomena can be described in terms of simple multistage models of carcinogenesis. The relationship of cancer risk with the different time variables considered corresponds closely with the behaviour predicted by theories of multistage process. Furthermore, the different behaviour associated with different agents enables one to attempt some classification as to how an agent is acting. There is considerable conformity between the tentative classification one might propose for the few agents for which epidemiological data are adequate, and the activity seen experimentally for these agents. The purpose of using multistage models in epidemiology is not simply descriptive. A distant goal would be the use of experimental information on mechanisms of action for the prediction of human risk. Information currently available is clearly insufficient, but the consistency seen between the epidemiological and experimental results suggests that some progress may be possible.