[Molecular epidemiology--methods and goals].

The prime focus of cancer epidemiology is the study of causal relations between exogenous exposure and clinical cancer. Molecular epidemiology is a promising new tool in the study of environmental carcinogens. Techniques of molecular epidemiology can be applied in assessing: internal "biological effective" dose by measuring carcinogen-DNA adducts; variation in individual susceptibility to carcinogens; carcinogen-specific genetic lesions for identification of tumorigenic chemicals in complex mixtures; early biologic effect, particularly mutations and other damage in cellular genes (molecular precancer), likely to be predictive of cancer. By incorporating biologic markers into epidemiologic studies, one can detect potential hazards early and increase the statistical power of studies to determine causal relationship. Such markers can also improve extrapolation of risks from experimental animals to humans.