Predictors of long-term survival in dogs with high-grade multicentric lymphoma

Objective-To determine factors predicting survival in dogs with high-grade multicentric lymphoma. Design-Retrospective cohort study. Animals-127 dogs with high-grade multicentric lymphoma evaluated at 4 veterinary hospitals from 2000 to 2009. Procedures-Records were reviewed to identify dogs with completely staged high-grade multicentric lymphoma treated withchemotherapy. Data collected included signalment, history, hematologic findings, tumor characteristics, treatment, and outcome. Long-term survival was defined as surviving>2 years after diagnosis. Variables were analyzed for associations with dogs living>2 years. Results-Among the 127 enrolled dogs, 13 (10%) survived>2 years with a median survival time of 914 days (range, 740 to 2,058 days). Survival rates at 3, 4, and 5 years were 4%, 3%, and 1%, respectively. At diagnosis, 11 of the 13 long-term survivors had a body weight ≥ 10 kg, PCV ≥ 35%, absence of ionized hypercalcemia, centroblastic lymphoma, immunophenotype B, absence of bone marrow involvement, and lymphoma stages I through IV and were not previously treated with corticosteroids. The same combination of factors was present in 26 of 114 (23%) dogs surviving≤2 years, yielding a negative predictive value of 97.8% for long-term survivors. Four of the 6 long-term survivors that died during the study died of another cancer; 3 of them had osteosarcoma. Conclusions and Clinical Relevance-Absence of the aforementioned combination of variables at diagnosis may help identify dogs with lymphoma that will not survive>2 years. Other types of neoplasia, in particular osteosarcoma, may develop in long-term-surviving dogs.