Mitomycin-C plus metronidazole in advanced carcinoma of the breast.

Twenty-seven patients with metastatic adenocarcinoma of the breast refractory to other chemotherapy were treated with mitomycin-C plus metronidazole. The mitomycin-C dose was 15-20 mg/m2 I.V. repeated every 6-9 weeks. Metronidazole 1.5 g/m2 was given p.o. 12 hr and 1 hr before mitomycin-C and again 6 hr and 24 hr after mitomycin-C. Partial remissions were noted in 4 of 24 (17%) evaluable patients. Good performance status patients who were lightly pretreated, unresponsive to prior chemotherapy, and estrogen receptor negative were most likely to respond, and further studies are indicated in this subgroup of patients. Hematological toxicity was similar to that anticipated with mitomycin-C alone. Gastrointestinal toxicity was probably increased. Three probable and 2 possible cases of pulmonary toxicity were seen. It is unclear whether the incidence of mitomycin-C pulmonary toxicity was increased by the metronidazole.