Prognostic factors for survival of dogs with inguinal and perineal mast cell tumors treated surgically with or without adjunctive treatment: 68 cases (1994-2002).

OBJECTIVE To determine the prognostic factors for survival and tumor recurrence in dogs with cutaneous mast cell tumors (MCTs) in the perineal and inguinal regions treated surgically with or without adjunctive radiation therapy, chemotherapy, or both. DESIGN Retrospective study. ANIMALS 68 dogs. PROCEDURE Medical records of dogs with histologically confirmed MCTs in the perineal region, inguinal region, or both treated surgically with or without adjunctive radiation therapy, chemotherapy, or both were reviewed. RESULTS Mean tumor-free interval was 1,635 days (median not reached), and 1- and 2-year tumor-free rates were 79% and 71%, respectively. Median survival time was 1,111 days (mean, 1,223 days), and 1- and 2-year survival rates were 79% and 61%, respectively. Factors that negatively influenced survival time were age at diagnosis, tumor recurrence, and treatment with lomustine. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dogs with MCTs in the inguinal and perineal regions, if appropriately treated, may have survival times and tumor-free intervals similar to dogs with MCTs in other locations.