A randomized trial of two dosage schedules of mitomycin C in advanced breast carcinoma

For mitomycin C (MMC), an effective agent in the treatment of metastatic breast cancer, the optimal dosing strategy in responding patients must be defined because of the dose-limiting, long-term hematologic toxic effects. Sixty-seven patients received treatment for metastatic breast cancer (MMC 20 mg/m2, intravenously) and then were selected randomly to receive either "standard doses" (SD) (20 mg/m2, intravenously) or "low doses" (LD) (5 mg/m2, intravenously) of MMC every 6 weeks. The primary objective was to show that the LD regimen would result in fewer toxic effects and at least equal disease control. Response rates in the two arms were similar: there were no complete responses and five partial responses (15%) in the SD group and two complete responses and six partial responses (24%) in the LD group (P = 0.332). In the SD and LD groups, median times to progression (11 versus 12 weeks, respectively), response duration (10 versus 6 1/2 weeks, respectively), and survival (26 versus 26 weeks, respectively) were similar. The hematologic toxicity was significantly less in the LD group. Nine patients in the LD group were treated with SD at disease progression, and one complete response was observed. It is concluded that, in this group of patients, administration of MMC in LD, compared with SD, resulted in fewer hematologic toxic effects and similar disease control.