Problems and perspectives in perinatal carcinogenesis: a summary of the conference.

The proceedings of the Conference are summarized in the context of current understanding of perinatal susceptibility to carcinogenic agents. The consequences of exposure to either metabolism-dependent or direct-acting chemical carcinogens during fetal or neonatal life are quantitatively different from the effects of comparable doses of the same agents in adults. The nature of these differences and their relevance both for preventive medicine and for application to bioassay procedures for detection of suspected carcinogens are discussed for conventional (chemically reactive) carcinogenic compounds and for hormones. The degree of tissue differentiation at the time of exposure to a carcinogen and the genetics of the subject have been shown to affect susceptibility to induction of embryonal and differentiated types of tumors and by both chemical agents (including hormones) and viruses. The desirability of conducting parallel studies in two or more species when investigating mechanisms of perinatal/adult differences in susceptibility to carcinogens is emphasized.