Canine Soft Tissue Sarcoma Managed in First Opinion Practice: Outcome in 350 Cases

OBJECTIVE: To determine outcome of dogs with a diagnosis of soft tissue sarcoma managed in first opinion practice. STUDY DESIGN: Retrospective, case-controlled study ANIMALS: Dogs (n = 350) with primary occurrence of a soft tissue sarcoma. METHODS: A previously validated questionnaire was sent to all veterinarians requesting clinical information and ultimate outcome for all dogs. Histologic sections were reviewed by a single pathologist. RESULTS: Most surgeries were unplanned, with only 15 (4%) dogs having a histologic and 59 (16.8%) dogs having a cytologic diagnosis before surgery. Median survival time for all dogs was not reached with 70% proportional survival at 5 years. Local recurrence developed in 73 (20.8%) cases. The extent of resection performed was not associated with improved survival (P = .2) or tumor recurrence (P = .8). Age <8 years (χ(2) = 6.1; P = .01), tumors <5 cm in size (χ(2) = 9.6; P = .002) and discrete tumors (χ(2) = 16.6; P < .001) had improved survival outcomes. On multivariate analysis, a high tumor grade was significant for recurrence (HR 5.8; P < .001; 95% CI: 2.2-14.8). Evidence of a selection bias towards less aggressive tumors being managed in first opinion practice was confirmed. CONCLUSIONS: Wide resection margins are not the primary determinant of outcome for all soft tissue sarcoma. Veterinarians need to better understand the biologic behavior of a suspected soft tissue sarcoma before treatment to allow surgical margins to be adjusted accordingly.