Docetaxel vs mitomycin plus vinblastine in anthracycline-resistant metastatic breast cancer

This nonblinded, multicenter, randomized phase III study compares the median time to progression (primary endpoint), response rate, and quality of life, safety, and survival of docetaxel (Taxotere) vs mitomycin (Mutamycin) plus vinblastine (Velban) in patients with metastatic breast cancer in whom previous anthracycline-containing chemotherapy has failed. Patients were randomized to receive an intravenous infusion of either 100 mg/m2 of docetaxel for 1 hour every 3 weeks, or 12 mg/m2 of mitomycin every 6 weeks plus 6 mg/m2 of vinblastine every 3 weeks. This preliminary analysis presents data on 200 patients among 392 patients recruited. Median time to progression was longer in the group treated with docetaxel compared with the mitomycin/vinblastine group (17 vs 9 weeks). The overall response rates were higher with docetaxel (28% vs 13%, respectively), and fewer patients in the docetaxel group had progressive disease as their best overall response (29% vs 48%). As expected, thrombocytopenia was more common in the mitomycin/vinblastine group, and neutropenia occurred more frequently in the docetaxel group. Severe fluid retention in the docetaxel group (8.7%) resulted in treatment discontinuation in 5 patients (5%). Severe thrombocytopenia (12%) and constipation (6%) led to treatment discontinuation in 7 and 3 patients, respectively, in the mitomycin/vinblastine group. Based on this preliminary analysis, docetaxel appears to be equally as safe as and more active than mitomycin/ vinblastine in patients with metastatic breast cancer in whom previous anthracycline-containing chemotherapy has failed. These results are subject to cautious interpretation because this analysis was conducted on the first 200 patients who finished the study treatments, and these preliminary results may underestimate response and overstate treatment discontinuation rates. Thus, the final analysis on the entire patient population is necessary to confirm these preliminary findings.