Combination chemotherapy in feline lymphoma: Treatment outcome, tolerability, and duration in 23 cats

Background: Different chemotherapy regimes have been described for feline lymphoma with varying outcomes. Hypothesis: In cats with lymphoma, a long-term, multiagent chemotherapy protocol will be effective and carry acceptable toxicity. Animals: Twenty-three cats with histologically or cytologically confirmed diagnosis of lymphoma. Methods: Prospective, single-arm clinical trial in which cats were treated with a chemotherapy protocol consisting of a cyclic combination of L-asparaginase, vincristine, cyclophosphamide, doxorubicin, methotrexate, and prednisolone with a planned total treatment time of 122 weeks. Results: Complete remission (CR) rate was 74% (n = 17). Fourteen percent of cats attained partial remission (PR). Median duration of first CR was 264 days (range, 45-2,485 days). Six-month, 1-, and 2-5-year remission rates were 75, 50, and 34%, respectively. Duration of PR ranged between 23 and 63 days. Median survival in cats with CR was 296 days (range, 50-2,520 days). Six-month, 1-, 2-, and 3-5-year survival rates in cats with CR were 82, 47, 34, and 27%, respectively. Survival of cats achieving PR ranged between 38 and 120 days. Of the analyzed variables, only anatomical location had a significant influence on remission duration (P=.022). Actual median treatment time in cats with CR was 128 days (18 weeks). Hematologic and gastrointestinal toxicosis was infrequent and mostly low grade. Conclusions and Clinical Importance: In this population of cats with lymphoma, chemotherapy was effective. With infrequent and mostly low-grade toxicosis, tolerability of the protocol may be considered good.