Neurotoxicity and efficacy of combined vinca alkaloids in breast cancer.

We treated 17 patients with metastatic breast cancer with the four-drug combination of vincristine (0.5-1.0 mg), vinblastine (4 mg/m2), doxorubicin (40 mg/m2), and cyclophosphamide (400 mg/m2). The two vinca alkaloids appeared to be synergistic in causing acute, reversible neurotoxicity, manifested primarily as diffuse pains involving one or more of jaws, limbs (particularly joints), chest, and abdomen. The response rate of 70% was no higher than that noted previously with a regimen identical to this one except for the exclusion of vincristine. Further studies of combined vinca alkaloids are not recommended in the treatment of breast cancer.