Response to medroxyprogesterone acetate (NSC-26386) as secondary hormone therapy for metastatic breast cancer in postmenopausal women.

We have treated 40 postmenopausal women with documented metastatic breast cancer with medroxyprogesterone acetate. The average age was 63 years and the patients were, on the average, 14 years' postmenopausal. Only two patients had received no prior additive hormone therapy. The remainder had previously received estrogen, androgens, or both. Only two patients had objective evidence of tumor regression. In one patient a metastatic node disappeared for 7+ months, and the other patient had well-documented clinical improvement and control of brain mestastases for 22 months. Two other patients had mixed responses of chest wall metastases (regression of some but not all lesions), lasting 3 and 4 months respectively. Five other patients had obvious subjective benefit. There were four objective responses (10%) and five subjective responses (12%). There was no correlation between route of administration and response. All patients receiving benefit had previously responded to other hormones. Side effects were usually absent or consisted of mild fluid retention; however, four patients had disease stimulation from therapy.