Use of surgery and electron beam irradiation, with or without chemotherapy, for treatment of vaccine-associated sarcomas in cats: 78 cases (1996-2000)

Objective-To evaluate responses of cats with vaccine-associated sarcomas to treatment with surgery and radiotherapy, with or without adjunctive chemot herapy. Design-Retrospective study. Animals-76 cats (78 tumors). Procedure-Medical records were reviewed. Factors potentially associated wit h survival time, time to recurrence, and time to development of metastases were evaluated. Results-Following excision, electron beam radiation, and, in some cases, ch emotherapy, 32 (41%) cats experienced recurrence, and 9 (12%) cats develope d metastases. One- and 2-year survival rates were 86 and 44%, respectively, Median survival time from onset of disease was 730 days (range, 30 to 2,01 4 days). Median disease-free interval was 405 days (range, 30 to 925 days). Cats that underwent only 1 surgery prior to radiotherapy had a lower recur rence rate than did cats that underwent > 1 surgery and had a significantly longer disease-free interval. Survival time and disease-free interval decr eased as time between surgery and the start of radiotherapy increased. Cats that developed metastases had significantly shorter survival times and dis ease-free intervals than did cats that did not develop metastases. Castrate d male cats had a significantly shorter survival time than did spayed femal e cats. Cats with larger tumors prior to the first surgery had shorter surv ival times. Twenty-six cats received chemotherapy in addition to surgery an d radiotherapy. Whether cats received chemotherapy was not associated with recurrence rate, metastasis rate, or survival time. Conclusions and Clinical Relevance-Results suggest that excision followed b y electron beam irradiation may be beneficial for treatment of cats with va ccine-associated sarcomas. Extent of excision prior to radiotherapy did not seem to be associated with recurrence rate.