Modifying factors in prenatal carcinogenesis (review).

A description of the experimental approaches devised to control the growth of tumors induced by transplacental exposure to carcinogens is given. Due to the massive cell proliferation and differentiation taking place during embryogenesis, fetal tissues are believed to be privileged targets of neoplastic changes. As a consequence, trace amounts of environmental carcinogens capable of accumulating into the conceptuses may determine the appearance of tumors in the offspring, a possibility documented in several animal species including humans. Endogenous and exogenous factors counteracting this process have potential application as regulators of developmental carcinogenesis. Their identification is regarded as a means to chemoprevent pediatric tumors and can be instrumental in the analysis of the aetiopathogenesis of neoplastic phenotypes.