Randomized trial of low- versus high-dose medroxyprogesterone acetate in the induction treatment of postmenopausal patients with advanced breast cancer.

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Abstract
In a randomized trial, 210 postmenopausal women with advanced measurable breast cancer were allocated to 2 schedules of medroxyprogesterone acetate (MPA). In the induction phase they received either 1000 mg i.m. MPA (high dose) daily or 500 mg i.m. MPA (low dose) twice weekly for 4 wk. The maintenance treatment consisted of 500 mg MPA i.m. once weekly for all patients. In total, 184 patients were considered evaluable. The response rate was significantly higher (P = 0.004) for patients receiving high-dose MPA (30 [33%] of 91) as compared to the women receiving the low-dose regimen (14 [15%] of 93) and was consistent across all prognostic subgroups. These prognostic subgroups included soft-tissue and osseous metastases, 2 metastatic sites, patients > 60 yr, disease-free interval > 60 mo., no prior chemotherapy, patients with a response to the last hormonal treatment before MPA, unknown estrogen receptors, and positive progestin receptors. The 2 different schedules of MPA did not influence the time to progression and the survival. Toxicity was similar in both regimens. These results confirm that a higher response rate can be achieved with a more intensive MPA schedule. This treatment may represent an ideal 2nd-line choice in the endocrine therapy of advanced breast cancer; however, its role as a 1st-line treatment remains to be defined.