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.