Efficacy of Maximum Dose Regimen Based on Patient and Prognostic Factors in R-CHOP Therapy for Older Patients with Diffuse Large B-Cell Lymphoma

Rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) therapy is the standard treatment for diffuse large B-cell lymphoma. However, optimal dosing in older patients remains unclear. At Hiroshima Citizens Hospital, an approach to define the maximum dose of cytotoxic anticancer drugs for patients ≥70 years commencing R-CHOP therapy was introduced in July 2020, based on age, Charlson Comorbidity Index, serum albumin (ACA Index), and the International Prognostic Index. The efficacy of this method was evaluated in this study. Patients were classified into pre- or post-implementation groups. The initial dose (actual dose relative to the standard dose), average relative dose intensity (ARDI) across all treatment cycles, 2-year progression-free survival (PFS) rate, and incidence of Grade 4 neutrophil count decreased (severe neutrophil count decreased) in the first cycle were compared between the groups. There were 27 patients in the pre-implementation group and 34 in the post-implementation group. The initial cytotoxic anticancer drug dose was significantly lower in the post-implementation group. However, there were no significant differences between the groups for ARDI (pre, 76％ vs. post, 72％) or 2-year PFS rate (pre, 73％ vs. post, 68％). In addition, 17 patients from each group were selected using propensity score matching. The incidence of severe neutrophil count decrease in the first cycle was significantly lower in the post-implementation group than in the pre-implementation group (pre, 71％ vs. post, 29％, P = 0.038). These results indicate that defining the maximum dose based on patient and prognostic factors may reduce the severity of decreased neutrophil count while maintaining ARDI and therapeutic outcomes.