Evaluation of clinical and histologic factors associated with survival time in dogs with stage II splenic hemangiosarcoma treated by splenectomy and adjuvant chemotherapy: 30 cases (2011-2014)

OBJECTIVE To determine histologic and clinical factors associated with survival time in dogs with stage II splenic hemangiosarcoma treated by splenectomy and a chemotherapy protocol in which an anthracycline was alternated with lomustine. DESIGN Retrospective case series. ANIMALS 30 dogs with stage II splenic hemangiosarcoma. PROCEDURES Medical records of 3 facilities were reviewed to identify dogs treated for stage II splenic hemangiosarcoma between June 2011 and October 2014. Information collected included signalment, disease staging data, whether anemia was present, date of splenectomy, chemotherapy protocol, adverse effects, and date of death or last follow-up. Histologic slides were reviewed and scored by pathologists. Associations between variables of interest and survival data were evaluated statistically. RESULTS Median survival time for all dogs was 158 days (range, 55 to 560 days), and the 1-year survival rate was 16%. On multivariate analysis, only the histologically determined mitotic score was significantly associated with survival time. The median survival time of 292 days for dogs with a mitotic score of 0 (< 11 mitoses/10 hpf; n = 9) was significantly longer than that for dogs with higher scores (indicating higher mitotic rates); the 1-year survival rate for these dogs was 42%. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that future studies should take histologic factors, particularly mitotic rate, as well as tumor stage into account when assessing treatment effects on survival time of dogs with splenic hemangiosarcoma.