Sequential Low-Dose Rate Half-Body Irradiation and Chemotherapy for the Treatment of Canine Multicentric Lymphoma

Background: Sequential half‐body irradiation (HBI) combined with chemotherapy is feasible in treating canine lymphoma, but prolonged interradiation intervals may affect efficacy. A 2‐week interradiation interval is possible in most dogs receiving low‐dose rate irradiation (LDRI) protocols at 6 Gy dose levels. Hypothesis: LDRI incorporated into a cyclophosphamide, doxorubicin, vincritine, and prednisone (CHOP)‐based chemotherapy protocol is effective for the treatment of lymphoma in dogs. Animals: Thirty‐eight client‐owned animals diagnosed with multicentric lymphoma. Methods: Retrospective study evaluating the efficacy and prognostic factors for the treatment of canine lymphoma with sequential HBI and chemotherapy. Results: The median 1st remission was 410 days (95% confidence interval [CI] 241–803 days). The 1‐, 2‐, and 3‐year 1st remission rates were 54, 42, and 31%. The median overall survival was 684 days (95% CI 334–1,223 days). The 1‐, 2‐, and 3‐year survival rates were 66, 47, and 44%. Conclusions and Clinical Relevance: Results of this study suggest that treatment intensification by a 2‐week interradiation treatment interval coupled with interradiation chemotherapy is an effective treatment for dogs with lymphoma.