Where splenic hemangiosarcoma spreads in dogs and what it means

Abstract

BACKGROUND: Splenic hemangiosarcoma (SHSA) is an aggressive neoplasm of dogs characterized by high metastatic rate and short survival time. Although staging and treatment are well established prognostic factors, the implication of specific metastatic sites remains unclear. HYPOTHESIS/OBJECTIVES: Describe the frequency and distribution of metastatic site at diagnosis in dogs with SHSA and evaluate the potential prognostic role of different metastatic locations. ANIMALS: Sixty-six dogs with histologically confirmed SHSA. METHODS: Retrospective, multicenter, descriptive study of dogs with SHSA treated by splenectomy. Data collected included demographics, clinical stage, and site of metastasis at diagnosis and at death, staging procedures, histopathology results, treatment protocols, and outcome. Survival analysis was conducted using Kaplan-Meier and Cox proportional hazards models. RESULTS: At diagnosis, three dogs were stage I (5%), 35 stage II (53%), and 28 stage III (42%). Overall median tumor-specific survival (TSS) was 132&#xa0;days. Stage III disease and hepatic metastases were associated with significantly decreased survival (P&#xa0;<&#xa0;.001). Dogs with liver metastasis that received anthracycline-based chemotherapy had longer survival compared with dogs that received metronomic therapy (255 vs 65&#xa0;days, P&#xa0;=&#xa0;.02). Muscular and pulmonary metastases did not correlate with worse outcomes. CONCLUSIONS AND CLINICAL IMPORTANCE: Stage and treatment were confirmed as prognostic factors, with patients in stage III and patients having received surgery alone having a worse prognosis. Although current staging classifies all metastatic disease as stage III, metastatic site may have variable impact on survival and should be considered when devising treatment strategy.