Metabolism of stilbene estrogens and steroidal estrogens in relation to carcinogenicity.

The oxidative metabolism of diethylstilbestrol (DES) and 17 alpha-ethynyl estradiol, as examples of stilbene- and steroid-type estrogens, is discussed with respect to the formation of reactive intermediates. For DES, a genotoxic potential is implied by metabolic studies and positive effects in short-term tests for genetic damage. A particularly important pathway for DES carcinogenicity appears to be peroxidase-mediated oxidation. Although data for steroidal estrogens are more ambiguous, the available evidence suggests that metabolic activation by peroxidatic oxidation may also be of importance for this class of estrogens.