Treatment of Breast Cancer with Medroxyprogesterone Acetate

Thirty-four postmenopausal women and two men disseminated breast cancer were treated with medroxyprogesterone acetate, a synthetic steroid with potent and specific progestational activity. Seven women demonstrated objective tumor regression. The mean duration of the response was 12 months. Tumor regression occurred in an additional five patients when the medroxyprogesterone acetate was combined with estrogens. A long "free interval" (from initial therapy to the appearance of distant metastases) and prior response to other hormones appeared to correlate with responsiveness to the progestogen. No serious drug toxicity was encountered.