Doxorubicin and cyclophosphamide for the treatment of canine lymphoma: a randomized, placebo-controlled study.

Median survival times (STs) for doxorubicin-treated canine lymphoma range from 5.7 to 9 months. Because dogs treated with multi-agent protocols have longer STs, we sought to evaluate whether adding cyclophosphamide would improve outcome in canine lymphoma patients while maintaining an acceptable level of toxicity. Thirty-two dogs with stage III-V multicentric lymphoma were treated with doxorubicin every 3 weeks for five total cycles and prednisone at a tapering dose for the first 4 weeks. Dogs were randomized to receive either cyclophosphamide or placebo concurrently. Seventeen dogs received doxorubicin and placebo, while 15 dogs received doxorubicin and cyclophosphamide. Response, toxicity, progression-free interval (PFI) and ST were evaluated. The combination of doxorubicin and cyclophosphamide was well tolerated, causing no increase in adverse events over doxorubicin alone. Despite a numeric improvement in outcome in cyclophosphamide treated dogs, the addition of cyclophosphamide did not result in statistically improved response rate, PFI or ST.