Use of Surgery and Electron Beam Irradiation

Use of Surgery and Electron Beam Irradiation, With or Without Chemotherapy, for Treatment of Vaccine-Associated Sarcomas in Cats: 78 Cases (1996-2000)
J Am Vet Med Assoc 219[11]:1582-1589 Dec 1'01 Retrospective Study 17 Refs

Michele Cohen, DVM; James C. Wright, DVM, PhD, DACVPM; William R. Brawner, Jr, DVM, PhD, DACVR; Annette N. Smith, DVM, DACVIM; Ralph Henderson, DVM, MS, DACVS, DACVIM; Ellen N. Behrend, VMD, PhD, DACVIM
Comparative Oncology Program, Animal Cancer Treatment Unit, and the Department of Pathobiology, CVM, Auburn University, Auburn, AL 36849-5523

OBJECTIVE: To evaluate responses of cats with vaccine-associated sarcomas to treatment with surgery and radiotherapy, with or without adjunctive chemotherapy.

PROCEDURE: Medical records were reviewed. Factors potentially associated with survival time, time to recurrence, and time to development of metastases were evaluated.

RESULTS: Following excision, electron beam radiation, and, in some cases, chemotherapy, 32 (41%) cats experienced recurrence, and 9 (12%) cats developed 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 2,014 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 recurrence rate than did cats that underwent > 1 surgery and had a significantly longer disease-free interval. Survival time and disease-free interval decreased as time between surgery and the start of radiotherapy increased. Cats that developed metastases had significantly shorter survival times and disease-free intervals than did cats that did not develop metastases. Castrated male cats had a significantly shorter survival time than did spayed female cats. Cats with larger tumors prior to the first surgery had shorter survival times. Twenty-six cats received chemotherapy in addition to surgery and radiotherapy. Whether cats received chemotherapy was not associated with recurrence rate, metastasis rate, or survival time.

CONCLUSIONS & CLINICAL RELEVANCE: Results suggest that excision followed by electron beam irradiation may be beneficial for treatment of cats with vaccine-associated sarcomas. Extent of excision prior to radiotherapy did not seem to be associated with recurrence rate.