Treatment of Oral Squamous Cell Carcinoma with Accelerated Radiation Therapy and Concomitant Carboplatin in Cats

Background Feline oral squamous cell carcinoma (SCC) carries a very poor prognosis with traditional treatments. Hypothesis/Objectives To examine the effectiveness of adding carboplatin to a previously published accelerated radiation protocol in the treatments of oral SCC in cats. Animals Thirty-one cases of oral SCC in cats. Tumor sites included lingual (n = 9), mandible (n = 10), maxilla (n = 7), tonsil (n = 4), and cheek (n = 1). Methods Prospective trial using a planned radiation protocol consisting of 14 fractions of 3.5 Gy given within a 9-day period with the addition of carboplatin given at 90-100 mg/m2 on day 1 and day 4.5. Treatments were twice daily with a 6-hour delay between treatments. All cats presenting with oral SCC without evidence of distant metastasis were eligible. Results Median survival for all cats was 163 days (range 53-770 days) with a mean of 319 +/- 53 days with significant predictors of survival being site (P = .004) and whether there was a complete response at 30 days (P = .001). Cats with tumors of tonsil origin or cheek responded best to therapy and were long-term survivors with a mean survival of 724 days and the median had not been reached because of continued survival of 4 cats. Conclusions and Clinical Importance This protocol offers an aggressive yet tolerable treatment of oral SCC in cats that might offer improved survival as compared with previously reported treatments. The long-term survival of cats with tonsillar SCC has not been reported previously.