Relation between adrenal function and 7, 12-dimethylbenz[a]-anthracene-induced mammary cancer of the rat.

The excretion of urinary steroids were investigated in rats in the course of mammary carcinogenesis by 7, 12-dimethylbenz [a] anthracene (DMBA). The carcinogen was fed to female Sprague-Dawley rats on days 50 and 64 after birth at a dose of 10 mg each. The excretion of urinary androgen, 11-deoxy-17-oxosteroid (11-DOOS), increased temporarily (at 80 days of age) in DMBA-treated rats as compared with non-treated controls. The excretion of adrenal corticosteroid, 17-deoxy-corticosteroid (17-DOCS), was lower than normal in the rats that failed to develop tumors within 200 days after receiving DMBA. The difference between the above non-responders and the tumor-developing responders (or the non-treated controls) was significant at 80 and 120 days of age, but not at 160 days of age. The final tumor weights at 160 days of age were also positively correlated to the excretion of 17-DOCS at 130 days of age. It was indicated that the overall process of DMBA carcinogenesis could be promoted by the endogenous adrenocortical steroids. The possible mechanism underlying the production of mammary cancer is discussed in the light of the metabolic intimacy between DMBA and the adrenal steroids.