Evaluation of tumor volume reduction of nasal carcinomas versus sarcomas in dogs treated with definitive fractionated megavoltage radiation: 15 cases (2010–2016)

Abstract Objective Local control is a major challenge in treating canine nasal tumors, and cytoreduction following radiation therapy has been recommended to extend survival and to delay local recurrence. Our objective was to compare the effect of definitive radiotherapy on the tumor volume of intranasal carcinomas compared to sarcomas. We evaluated 15 dogs that received radiotherapy within 1 month of initial CT scan, and post radiation CT scans performed within 3 months of completing full course definitive megavoltage radiation. Tumor reduction volume based on CT scans were obtained and compared between carcinoma and sarcoma groups. Results The following tumor types were treated; carcinoma (8/15), sarcoma (7/15). The mean nasal tumor size before radiation therapy was 24.5 cm3 and tumor size after radiation therapy was 13.5 cm3 resulting in a mean reduction of 55.1% reduction in tumor size for both carcinomas and sarcomas. The carcinoma group displayed a volume reduction of 67.1% (SD ± 16.9) and the sarcoma group displayed a volume reduction of 21.3% (SD ± 39.7). Within the study period carcinomas were more responsive in the reduction of volume than sarcomas with fractionated megavoltage radiation.