Mitomycin C in large infrequent doses in breast cancer.

Seventy-one women with far-advanced breast cancer resistant to standard chemotherapeutic agents were administered mitomycin C using an intermittent high dose schedule. One group consisted of 54 patients with measurable metastatic tumor; a second group consisted of 18 patients with nonmeasurable osseous metastases. Objective response rate in group 1 was 26% for an average duration of 2 1/2 months. Subjective response rate in group 2 was 44% for an average duration of 3 months. Response and toxicity data were similar to those of studies employing the less convenient protracted low-dose schedule. Prior treatment with other alkylating agents did not adversely affect response. Further investigation into the role of mitomycin in combination chemotherapy programs is recommended.