Chemotherapy with mitomycin C and vinblastine in pretreated metastatic breast cancer.

AIMS: In February 1986 we began a study to test the activity of mitomycin C (12 mg/m2) plus vinblastine (6 mg/m2) on day 1 of a 28-day cycle (MV) as second or third-line chemotherapy for metastatic breast cancer patients. METHODS: As of February 1988 the study was stopped after 26 patients had been enrolled. The median age of the patients was 54 years (range 35-78); all patients were progressive from chemotherapy; 15 (57.7\%) patients were treated as second and 11 (42.3\%) as third line; 19 (73.1\%) patients had received anthracyclines as first (13 patients) or second-line (6 patients) chemotherapy; 18 (69.2\%) patients had visceral involvement; 7 (26.9\%) had one metastatic site, 11 (42.3\%) two sites, 6 (23.1\%) three sites and 2 (7.7\%) four sites. RESULTS: Overall, 86 cycles were administered, with a median number of 3 cycles per patient. Toxicity was mild; hematologic side effects required discontinuation of treatment in 3 cases. Vomiting occurred in 3 (11.5\%) patients, nausea in 5 (19.2\%). Moderate neurologic toxicity was recorded in 6 (23\%) patients. No complete and 3 partial responses were observed. The objective response rate was 11.5\% (exact 95\% confidence interval, 2.4-30.1). Responses occurred independently of disease-free interval, dominant metastatic site, response to previous chemotherapy, previous anthracycline and line of treatment; all responses were recorded in patients under 50 years of age. Kaplan-Meier estimated median time to progression and overall survival were 13 and 40 weeks, respectively. CONCLUSION: The MV regimen was well tolerated but showed little activity in pretreated metastatic breast cancer.