Outcome following treatment of feline gastrointestinal mast cell tumours

Prognosis of feline gastrointestinal mast cell tumours (FGIMCT), based on limited available literature, is described as guarded to poor, which may influence treatment recommendations and patient outcome. The purpose of this study is to describe the clinical findings, treatment response, and outcome of FGIMCT. Medical records of 31 cats diagnosed with and treated for FGIMCT were retrospectively reviewed. Data collected included signalment, method of diagnosis, tumour location (including metastatic sites), treatment type, cause of death and survival time. Mean age was 12.9y. Diagnosis was made via cytology (n=15), histopathology (n=13) or both (n=3). Metastatic sites included abdominal lymph node (n=10), abdominal viscera (n=4) and both (n=2). Therapeutic approaches included chemotherapy alone (n=15), surgery and chemotherapy (n=7), glucocorticoid only (n=6) and surgery and glucocorticoid (n=3). Lomustine (n=15) and chlorambucil (n=12) were the most commonly used chemotherapy drugs. Overall median survival time was 531d (95% confidence interval 334, 982). Gastrointestinal location, diagnosis of additional cancers, and treatment type did not significantly affect survival time. Cause of death was tumour-related or unknown (n=12) and unrelated (n=8) in the 20 cats dead at the time of analysis. The prognosis for cats with FGIMCT may be better than previously reported, with 26% of cats deceased from an unrelated cause. Surgical and medical treatments (including prednisolone alone) were both associated with prolonged survival times. Treatment other than prednisolone may not be necessary in some cats. Continued research into prognostic factors and most effective treatment strategies are needed.