Hormone-associated cancer: mechanistic similarities between human breast cancer and estrogen-induced kidney carcinogenesis in hamsters.

Estrogens are risk factors for human breast cancer and induce kidney tumors in Syrian hamsters. Mechanistic features of the estrogen-induced hamster kidney tumor model have been compared with corresponding aspects of human breast cancer to gain insight into the mechanism of human mammary oncogenesis. Shared characteristics point to a mechanism of metabolic activation of steroidal estrogens to 4-hydroxylated catechol metabolites that may undergo metabolic redox cycling, a mechanism of generation of reactive free radicals. Tumors may arise in cells genetically altered by various types of estrogen-induced DNA damage. At the same time, these altered cells may respond to estrogen receptor-mediated stimuli in support of cell transformation and growth.