Background: Standard of care for dogs with high-grade lymphoma, multiagent chemotherapy, achieves good initial responses but long-term remissions are infrequent; previous studies using half-body irradiation suggest improved long-term outcomes.
Hypothesis: The addition of low-dose rate half-body irradiation would improve outcomes in dogs with B-cell lymphoma.
Animals: Client-owned dogs with stage III or higher, substage a, B-cell lymphoma that achieved complete remission after 4 doses of multiagent chemotherapy.
Methods: A case-controlled design comparing 2-year remission and survival rates between dogs treated with CHOP-based chemotherapy and those treated with chemotherapy and sequential low-dose rate half-body irradiation.
Results: Thirty-eight dogs were enrolled with 18 included in final analysis, 9 prospectively-enrolled dogs and 9 case-matched historical controls. The irradiation cohort's 2-year disease-free rate was 56% whereas median duration exceeded the 730-day study period compared with 0% and 261 days in the chemotherapy only group. Remission duration significantly differed between cohorts (P < .01), hazard ratio 0.218 (95% CI: 0.06-0.77). The irradiation cohort's 2-year survival rate was 78% with median overall survival duration exceeding the 730 day study period compared with 11% and 286 days in the chemotherapy only group. Overall survival time significantly differed between cohorts (P < .02), hazard ratio 0.173 (95% CI: 0.03-0.839).
Conclusions and clinical importance: The improved long-term outcome achieved by dogs administered sequential low-dose rate half-body irradiation in this study is similar to previous observational studies. Where long-term remission is sought in dogs with B-cell lymphoma low-dose rate half-body irradiation could be considered in addition to standard chemotherapy.
Keywords: CHOP; controlled; cure; radiation therapy.
© 2023 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC. on behalf of the American College of Veterinary Internal Medicine.