[Administration method and recurrence-preventing effect of medroxyprogesterone acetate (MPA) as a postoperative adjuvant endocrine therapy for stage III breast cancer. Kitakyushu Collaborative Study Group for Breast Cancer].

By a collaborative study undertaken by 11 medical institutions in the Kita-Kyushu area, we evaluated the clinical efficacy of the combination of medroxyprogesterone acetate (MPA) and Tamoxifen (TAM) as a postoperative adjuvant endocrine therapy for Stage III breast cancer. First, 1 course of CAF therapy was administered; then, in combination with the basic therapy of 5-FU 200 mg/day p. o. for 3 years, ER (+) patients were treated with either 2-week sequential therapy of TAM (30 mg/day) and MPA (800 mg/day) or TAM (30 mg/day), and ER (-) patients received either MPA (800 mg/day) or 5-FU alone. Neither survival nor disease-free rates of the 92 analyzable patients were different between these treatment groups. Furthermore, the blood levels of MPA and cortisol had no correlation with survival and disease-free periods. We studied the effect of MPA on the natural inhibitors of blood coagulation, but found no difference from the result in healthy adults. It was, however, shown that MPA had a bone marrow-protecting effect.