Addition of rituximab to the CHOP regimen has no benefit in patients with primary extranodal diffuse large B-cell lymphoma

BACKGROUND The addition of rituximab to cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy (R-CHOP) has significantly improved clinical outcomes for patients with diffuse large B-cell lymphoma (DLBCL). However, new predictors of patient response to R-CHOP have not been established. We aimed to evaluate the impact of R-CHOP compared with CHOP in patients with DLBCL and to establish clinical predictors of better outcomes in these patients. METHODS We retrospectively identified 177 patients diagnosed with CD20-positive DLBCL and treated with CHOP (N=82) or R-CHOP (N=95). The response rate, event-free survival (EFS), and overall survival (OS) rates were compared between the 2 treatment groups. All patients were classified into primary extranodal lymphoma (PENL) or nodal lymphoma (NL) subgroups, and the clinical parameters of each subgroup were analyzed. RESULTS The overall response rate was higher in R-CHOP group (95% vs. 84%, P=0.07). The 3-year EFS rate was significantly higher in R-CHOP group (71% vs. 52%, P=0.013), but the OS rate was comparable between the 2 groups (79% vs. 69%, P=0.23). A significant survival benefit was seen with R-CHOP compared to CHOP therapy in NL patients (P=0.002 for EFS and 0.04 for OS). Multivariate analyses confirmed that R-CHOP therapy is an independent prognostic factor for EFS (hazard ratio of 0.32 [0.17-0.62], P=0.001) and OS (hazard ratio of 0.4 [0.18-0.87], P=0.02) in NL patients. CONCLUSION Patients in the PENL group did not benefit from R-CHOP chemotherapy.