Outcomes of dogs with grade 3 mast cell tumors: 43 cases (1997-2007).

This study reports the outcomes of dogs with grade 3 mast cell tumors (MCTs). Clinical and histopathological data were available for 43 dogs. Median progression-free survival (PFS) and overall survival (OS) were 133 and 257 days, respectively. Tumor size, lymph node (LN) status, and mitotic index (MI) significantly influenced PFS in univariate analysis. Tumor size and LN status remained significant in the multivariate analysis. Lymph node status, local tumor control, LN treatment, and MI significantly influenced OS in univariate analysis but only LN status remained significant in multivariate analysis. These results confirm that locoregional control improves outcomes in patients with grade 3 MCTs.