Response of feline oral squamous cell carcinoma to palliative radiation therapy.

Seven cats with advanced oral squamous cell carcinoma were treated with palliative radiotherapy. Megavoltage radiation in 8 Gray (Gy) fractions was delivered on days 0, 7, and 21 for a total dose of 24 Gy. Treatment field included the mandible, oropharynx, retropharyngeal lymph nodes, and tonsils. Adjuvant treatment with chemotherapy was variable. Age ranged from 13 to 18 years old with a median age of 15 years. Three of the seven cats (43%) did not complete treatment. Six cats were euthanized due to tumor growth and/or radiation side effects with a median survival time of 60 days (range = 42 to 97 days, mean = 63 +/- 8.4 days). Radiotherapy complications or progression of disease occurred in 6 of 7 (85.7 %) cats and included adverse clinical signs, such as mucositis, serosanguinous oral discharge, pain, and dysphagia. These data suggest that coarse fractionation radiotherapy did not result in palliation in cats with inoperable oral squamous cell carcinoma.