Vinblastine and prednisolone chemotherapy for surgically excised grade III canine cutaneous mast cell tumours.

The effect of treatment with vinblastine and prednisolone chemotherapy in dogs undergoing only surgical excision of Patnaik grade III cutaneous mast cell tumours is reported. Potential explanatory variables were explored using Kaplan-Meier survival analysis with log-rank tests. During a median follow-up period of 429 days, the overall median survival time (MST) was not reached (lower 95% CI = 322 days). The 1-year survival probability was 0.71 (standard error 0.1), remaining unchanged at 2 years. Secondary disease at presentation was an independent risk factor for survival (P = 0.045). The MST of dogs presenting with secondary disease was 322 days, with a lower 95% confidence interval of 142 days and a 1-year survival of probability of 0.47 (standard error 0.19). Adverse effects were recorded in 6 of the 108 (5.6%) vinblastine doses given. This chemotherapy regimen is a well-tolerated adjunct to surgery for grade III mast cell tumours and appears to prolong survival compared with that expected with surgery alone.