The effect of 7beta, 17alpha-dimethyltestosterone (calusteron) on testosterone metabolism in women with advanced breast cancer.

Calusterone (7beta, 17alpha-dimethyltestosterone) is a 17-alkylated, orally active androgenic steroid used in the treatment of breast cancer. The effect of this steroid on the metabolism of 14C-testosterone and the excretion of endogenous urinary androgen metabolites has been studied in four patients with breast cancer. Total glucuronide metabolites of the tracer decreased significantly, the andorsterone/etiocholanolone ratio rose by a factor of 2-4, and there was increased formation of uncharacterized polar metabolites. There was no significant change in either the sum of the excretion of endogenous androgen metabolites or the androsterone/etiocholanolone ratio. The changes resemble those we have seen in cirrhosis of the liver. It is concluded that the effects of Calusterone on testosterone metabolism, like its effects on cortisol or estradiol metabolism, represent nonspecific effects of an orally administered 17-alkylated steroid on hepatic structure and function, and probably bear no relationship to its therapeutic effect in breast cancer.