[Estradiol-2-hydroxylase activity in tumors of the corpus uteri and breast: the effect of smoking]

The levels of estradiol-2-hydroxylase were assayed in patients with breast (17) and endometrial (30) tumors. In the latter group, the findings were compared with normal endometrium and the enzyme was found in it, too. A direct correlation was established between age and said level in tumor tissue in nonsmokers, particularly, in breast cancer cases. Smokers revealed relatively higher levels both in tumor tissue and normal endometrium. No relationship between estradiol-2-hydroxylase and steroid hormone receptor concentrations was found in either endometrial or breast tumors. The role of estrogen metabolism and conversion of classical estrogens to catecholestrogens in hormone-related carcinogenesis is discussed.