Combination chemotherapy with mitomycin C and methotrexate is active against metastatic HER2-negative breast cancer even after treatment with anthracycline, taxane, capecitabine, and vinorelbine

Background: Combination chemotherapy with mitomycin C and methotrexate (MM) was reported to be effective for 24% of patients with metastatic breast cancer (MBC) who had been treated with anthracycline and taxane. Antimetabolites such as capecitabine and antitubulins such as vinorelbine have been generally used for MBC treatment after anthracycline and taxane. A subsequent choice of chemotherapy should be offered to patients with MBC who have kept good performance status (PS) after being aggressively treated with anthracycline, taxane, capecitabine, and vinorelbine (ATCV), but is not well clear which treatment is superior to others after ATCV. In this study, we examined whether MM treatment is a good choice following ATCV. Methods: We retrospectively reviewed the medical records of 31 patients with HER2-negative metastatic breast cancer who were treated with MM following ATCV. One cycle of MM was defined as MMC 8 mg/m(2) on day 1 and MTX 60 mg/m2 on day 1 and day 15, administered intravenously every 4 weeks. Results: Response rate and clinical benefit rate were 9.7 and 19.4%, respectively. Median times to progression and times to failure were 3.9 and 3.7 months, respectively. Adverse events of grade 3 and/or 4 were observed in 36% patients. Thrombocytopenia of grade 3 or 4 was 12.9 and 3.2%. Grades 3 and 4 of leucopenia and anemia were 12.9 and 9.7%, respectively. Conclusion: MM is effective and tolerable for MBC patients even after aggressive treatment with ATCV. MM is one treatment choice when patients have kept good PS and bone marrow function even after multiple regimens of chemotherapy.