Rituximab in combination with CHOP chemotherapy for the treatment of diffuse large B cell lymphoma in Japan: a retrospective analysis of 1,057 cases from Kyushu Lymphoma Study Group.

We performed a retrospective analysis of patients with diffuse large B cell lymphoma treated with rituximab plus CHOP (cyclophosphamide, adriamycin, vincristine and prednisone) as a first-line therapy at 22 hospitals of the Kyushu Lymphoma Study Group. During the period 1996-2005, 1,057 patients (aged 22-90 years) were analyzed. Of these, 678 were treated with CHOP, and 379 were treated with rituximab plus CHOP (R-CHOP). The complete response rate was 59.9% in the CHOP group and 67.0% in the R-CHOP group (P < 0.001). Three-year progression-free survival (PFS) and overall survival (OS) rates were significantly higher in the R-CHOP group than in the CHOP group (61.3 vs. 45.6% for PFS, P < 0.001; 68.3 vs. 54.5% for OS, P < 0.001). The International Prognostic Index was a good prognostic marker for both groups; a survival benefit of rituximab addition was found for each risk subgroup and also for both age groups (<or=60 and >60 years). Among 345 patients who received localized radiation therapy, the adding rituximab to CHOP attenuated the survival difference between CHOP and R-CHOP groups (P = 0.104), compared with no radiation group (P < 0.001). Results of this large-scale, multicenter study confirm that rituximab plus CHOP provided a greater survival benefit than CHOP alone.