High dose medroxyprogesterone acetate (MPA) treatment in metastatic carcinoma of the breast: a dose-response evaluation

Abstract

The results of controlled clinical trial that used high doses of medroxyprogesterone acetate (MPA) in the treatment of metastatic breast cancer are reported. Two treatment reigmens were used: regimen A, 500 mg daily with a total dose of 30 g; regimen B, 1,000 mg daily with a total dose of 60 g. The overall response rates were similar, with no statistically significant difference between the two treated groups. Regimen A (lower dosage group) reached a remission rate of 44%, whereas regimen B (higher dosage group) had a remission rate of 41%. The mean duration of response was 8 months with regimen A and 9 months with regimen B. The advantages of the lower dosage regimen as opposed to the higher dosage regimen of MPA in the treatment of advanced breast cancer are discussed.

PIP: A controlled clinical trial that used high doses of medroxyprogesterone acetate (MPA) in the treatment of metastatic breast cancer was conducted. Therapy consisted of 2 treatments: regimen A, 500 mg daily with a total dose of 30 g; regimen B, 1000 mg daily with a total dose of 60 g. From June 1975 to September 1976, 101 patients entered into the study and were randomly allocated into the 2 treatment groups. Both treatment groups were comparable in terms of age, menopausal status, free interval, and dominant site of lesions. Selection of patients was done according to the following criteria: histologically proved progressive metastatic carcinoma of the breast, without any treatment for at least 2 months; no prior hormonal manipulation; performance status 50 or more, and life expectancy longer than 3 months; measurable disease. Overall response rates were similar, with no statistically significant difference between the 2 treated groups. Regimen A reached a remission rate of 44%; regimen B had a remission rate of 41%. The mean duration of response was 8 months with regimen A and 9 months with regimen B. Both regimens were well tolerated. Clinical toxicity was mild with both dosages of MPA. The main side effect was gluteus abscess, with a higher incidence in group B. This was probably due to the greater amount of injected drug suspension in the 1000 mg/day regimen. The incidence of thrombophlebitis and vaginal bleeding was negligible.