A Retrospective Study Evaluating the Outcomes of Conventionally Fractionated Radiation Therapy as a Treatment for Infiltrative Lipomas in Twenty-One Dogs.

Infiltrative lipomas represent a subcategorisation of rarer, potentially more aggressive, lipoma-related neoplasms. Twenty-one dogs treated with conventionally fractionated radiotherapy (CFRT) for infiltrative lipomas were included in this retrospective study. One patient had no prior surgical excision, 11 patients had one prior surgery and 9 patients had two or more surgeries prior to CFRT. Five patients (24%) had microscopic disease and 16 patients (76%) had macroscopic disease prior to treatment. A complete response or no regrowth was seen in 10 patients (48%), stable disease in 6 patients (29%) and progressive disease or regrowth in 5 patients (24%). Response to treatment of macroscopic tumours was significantly different between dogs that had one prior surgery versus two or more (p = 0.01). Dogs with a single surgery were most likely to result in stable disease compared with dogs with two or more surgeries resulting in a complete response. The dog without surgery developed progressive disease at 211 days, dogs with one surgery had a median progression or recurrence at 1369 days and dogs with two or more surgeries developed progression or recurrence at 826 days (p = 0.04). Twelve dogs were alive at the time of analysis. Overall median survival time (MST) was 1694 days. The prior number of surgeries did not significantly affect MST. While survival time is comparable to previous reports, the number of patients with progressive disease or recurrence of previous microscopic disease requires more investigation into the most appropriate protocol, dose and treated field size.

Successful definitive radiation treatment of refractory canine oral papillomatosis.

This case report describes a three-year-old male intact border collie diagnosed with canine papillomavirus type 1 (CPV-1+) oral papillomas resistant to standard-of-care. With time, he developed lesions consistent with squamous cell carcinoma. Malignant tumors were incompletely excised and treated with definitive external beam radiation therapy (45 Gy, 3 Gy × 15 daily). The remaining oral cavity received 27 Gy (1.8 Gy x 15 daily) to treat the disseminated oral papillomatosis. A temporary treatment delay of 2 weeks was instituted due to grade 3 mucositis. The patient remained in complete remission after 10 months from radiotherapy. No tumor recurrences were noted by the owners after >1 year from treatment.