Carcinogen activation by human uterine enzymes

Three topics are briefly reviewed relating to carcinogenesis of estrogen responsive tissues: (a) enzymology of benzo(a)pyrene activation by human tissues, (b) microsomal activation of estrogens to estrogen arene oxides and (c) estrogen and progesterone receptor studies in endometrial carcinoma. The following working hypothesis is stated on the etiology of gynecologic tumors: "Environmental chemicals, such as cigarette smoke, polycyclic and polyhalogenated hydrocarbons, etc., induce special forms of cytochrome P-450 monooxygenase and related enzyme systems which can activate endogenous or prescribed estrogens and non-steroid antiestrogens to act as initiators and/or promoters of neoplasia in estrogen-dependent organs." The role of estrogen receptors is perceived as a homing device or cellular "Trojan Horse" for these activated estrogens.