RESUMO
Seventy-five patients with advanced and intensively pretreated breast cancer received high-dose medroxyprogesterone acetate (MPA) using a schedule consisting of an intramuscular (IM) loading dose (1 g MPA IM days 1 to 10) and an oral maintenance treatment (200 mg/day three times a day) thereafter. A reinduction was performed in part of the responding patients at time of early relapse (1 g MPA IM for 10 consecutive days). MPA serum levels above 100 ng/ml were achieved during induction treatment and maintained for 3 to 4 months during the oral phase of therapy before decreasing to approximately 50 ng/ml. Two complete remissions (duration, 17.2 and 62 months), 15 partial remissions (median duration, 7 months), and 21 cases of disease stabilization (median duration, 5.5 months) were achieved. The median survival time was significantly longer for responders (19.9 months) than nonresponders (4.8 months). Although a higher proportion of postmenopausal patients responded, the remission duration in premenopausal women was remarkably long. Favorable sites of response were soft tissue, lymph nodes, and bone lesions. Reinduction treatment yielded a second response (two partial remissions, three no change) in five of six patients indicating that high-dose conditions were necessary to maintain response. This schedule allows to restrict higher doses of MPA on a long-term basis to responding patients.
