PROSPECTIVE-STUDY OF RADIATION-THERAPY FOR THE TREATMENT OF GRADE-2 MAST-CELL TUMORS IN 32 DOGS

Surgery, chemotherapy, and irradiation have been used singly or in com bination to treat dogs with cutaneous grade-2 mast cell tumors (MCT). However, optimal treatment has not been established, At The Animal Med ical Center, 32 dogs with grade 2, stage 0 MCT received cobalt radiati on treatment to a dose of 54 Gy; 94% had a disease-free interval of 1 year. The 2-,3-,4-, and 5-year disease-free intervals were 86%. Surviv al rates were 100% for 1 year and 96% for 2 to 5 years, with only 1 de ath caused by MCT. primary site was not a prognostic factor for surviv al in this study. Minimal toxicity was observed and was limited to acu te cutaneous reactions. Late-term reactions to radiation therapy were mild and considered acceptable in all cases. No deaths occurred due to treatment, and no dog was eliminated from the study because of radiat ion therapy toxicity. Radiation therapy appears to be an effective tre atment for dogs with grade 2, stage 0 MCT. Copyright (C) 1996 by the A merican College of Veterinary Internal Medicine.