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; 0, 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; 0, vincristine; and P, prednisone) with maintenance therapy (COAP group) or a 19-week CHOP (C, cyclophosphamide; H, doxorubicin; 0, 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.