[Phase II study of medroxyprogesterone acetate in advanced breast cancer]

A phase II study of high-dose medroxyprogesterone acetate (MPA) was performed in 18 patients with advanced breast cancer. MPA was administered at a dosage of 1,200mg orally per day. Of the 15 evaluable patients, partial response was obtained in 3, minor response in 1, no change in 5 and progressive disease in 6 patients. The response rate was 20%, which was as effective as that of tamoxifen. As the responders had been previously treated with tamoxifen, the result suggested that MPA showed no cross-resistance to the latter. Eight patients (53%) experienced weight gain which, in 4 cases (27%), necessitated discontinuation of the treatment. One patient exhibited an allergic reaction and the drug was discontinued. Palpitation in 4 patients (27%), vaginal bleeding in 2 (13%), and edema in 1 (7%) were observed, but these effects were tolerable. We therefore conclude that high-dose MPA is an effective therapy for advanced breast cancer, and that further study is warranted.