Adjuvant Therapy with High-Dose Medroxyprogesterone Acetate for Operable Breast Cancer

BACKGROUND: Medroxyprogesterone acetate (MPA) produces a comparable or higherresponse rate in metastatic breast cancer compared with tamoxifen which is alsocommonly used for adjuvant endocrine therapy. Several studies in the West have indicated the efficacy of MPA when used as an adjuvant to surgery in certain subsets of patients. The present study was undertaken as a multicenter open study in Japan to investigate the safety and efficacy of MPA in adjuvant endocrine therapy. Method and Patients: A combination of 800 mg/day MPA and a fluorouracil compound for 6 months was given postoperatively to 119 patients with stage II or IIIabreast cancer in 32 participating hospitals between June 1987 and June 1989. RESULTS: Among the 119 patients, 59 patients (49.6%) experienced some kind ofadverse reaction. The major adverse reaction was abnormal menstruation, seen in 13 (25.0%) of the 52 premenopausal patients. Vaginal bleeding was a major adverse reaction in the 67 postmenopausal patients (8/67 or 11.9%). An increase in body weight and moon face were observed in 23 (19.3%) and 9 (7.6%) of the 119 patients, respectively. Administration of drugs was discontinued because of adversereaction in 17 patients (14.3%), and dose reduction or temporary suspension wasnecessary in 7 patients (5.9%). Increase in body weight was the main reason fordiscontinuation of the treatment. No severe adverse reactions were observed. After a median follow-up of 74.5 months (range, 2.2-90.0 months), 84 of the 119 patients are alive with no evidence of disease. The 3-year and 5-year disease-freesurvival rates were 88.2% and 82.6% in stage II patients, and 64.7% and 52.9% in stage IIIa patients, respectively. The 3-year and 5-year disease-free survivalrates according to age were 87.8% and 79.3% in patients aged 50 years or more, and 78.6% and 71.4% in patients aged under 50 years. CONCLUSION: These results show that 800 mg/day MPA plus a fluorouracil compound can be administered with acceptable morbidity as an adjuvant treatment to selected breast cancer patients.