Effective palliative treatment of recurrent soft tissue sarcoma in a dog using imatinib mesylate (Gleevec®)

Abstract

A 14-year-old neutered female Yorkshire terrier presented with a rapidly growing gluteal mass. There was a history of surgical resection of a mass diagnosed as a grade two soft tissue sarcoma in the same region a year earlier. The second mass was surgically excised and histopathologically diagnosed as grade two soft tissue sarcoma. A further relapse occurred six months after the second surgery. On that occasion, the dog was treated with metronomic chemotherapy consisting of cyclophosphamide and piroxicam, which failed to adequately control the disease and the mass increased 2.5-fold in size in three weeks. Imatinib treatment was started, after which there was a 62% reduction in the size of the mass. The patient has remained in partial remission for five months. To the authors' knowledge, this is the first report on the use of imatinib to treat canine soft tissue sarcoma. Imatinib might be a useful treatment for soft tissue sarcoma that recurs after surgical resection.