Comparison of the Efficacy of 15- and 19-Week Chemotherapy Protocols Based on Vincristine, L-Asparaginase, Doxorubicin, and Prednisolone for Dogs with Multicentric Lymphoma

Multicentric lymphoma is the most common type of hematopoietic neoplasm in dogs. Chemotherapeutic protocols typically consist of cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP). The 15- and 19-week CHOP protocols exhibit similar outcomes, indicating that a shorter treatment duration may be a feasible treatment option. However, the 19-week LHOP protocol, which uses L-asparaginase instead of cyclophosphamide, results in a longer progression-free survival and a similar survival time compared to CHOP-based chemotherapy regimens. In this study, we conducted and historically compared the efficacy of the 15- and 19-week LHOP protocols to determine whether there are any differences in efficacy. Eighteen and twenty dogs underwent the 15- and 19-week LHOP protocols, respectively. No significant differences were found in age, body weight, sex, clinical stage, substage, T-cell phenotype, hypercalcemia status, and overall response rate between the two groups. The time to progression (TTP) and lymphoma-specific survival (LSS) for the 19-week LHOP protocol were significantly longer than those for the 15-week LHOP protocol (<i>p</i> = 0.004 and <i>p</i> = 0.008, respectively). Thus, the 19-week LHOP protocol may be a better treatment option for dogs with multicentric lymphoma. However, the 15-week LHOP protocol lowered the treatment cost and reduced the treatment time.