Comparison of COAP and UW‐19 Protocols for Dogs with Multicentric Lymphoma

Background: Various chemotherapy protocols for treating lymphoma in dogs have been published; however, comparison of protocols from different studies is difficult, especially when evaluating survival time and toxicoses. Hypothesis: The choice of COAP (C, cyclophosphamide; O, vincristine; A, cytosine arabinoside; P, prednisone) and a modified University of Wisconsin 19-week (UW-19) induction protocol has no influence on overall survival times in dogs with lymphoma. Animals: One hundred and one dogs with multicentric lymphoma. Methods: Retrospective study (2001–2006). Dogs induced with either an 8-week COP-based protocol (C, cyclophosphamide; O, vincristine; and P, prednisone) with maintenance therapy (COAP group) or a 19-week CHOP (C, cyclophosphamide; H, doxorubicin; O, vincristine; and P, prednisone) based protocol (UW-19 group) were compared in terms of the duration of first remission, survival time, toxicoses, and cost. Results: There were 71 dogs in the COAP group and 30 dogs in the UW-19 group. Various protocols were used after the first relapse. The median duration of the first remission for the COAP and UW-19 groups were 94 days (range, 6–356 days) and 174 days (28–438 days), respectively (P < .01). The median survival times for dogs in the COAP and UW-19 groups were 309 days (6–620 days) and 275 days (70–1102+ days), respectively (P= .09). Dogs in the COAP group had a hazard ratio of 1.9 (95% CI 1.1–3.4) for death relative to the UW-19 group (P= .03), after controlling for the confounders (World Health Organization clinical stage, age, sex, use of doxorubicin during reinduction). The severity of neutropenia and gastrointestinal toxicoses were significantly higher in the UW-19 group than in the COAP group (P= .01 and P < .01, respectively). Conclusion and Clinical Importance: Use of a long-term doxorubicin-containing sequential combination chemotherapy protocol is associated with a decreased risk of relapse and death relative to a non-doxorubicin-containing protocol.