Clinical Outcome of Rituximab-Based Therapy (RCHOP) in Diffuse Large B-Cell Lymphoma Patients with Bone Marrow Involvement

PURPOSE We investigated the clinical outcome of bone marrow (BM) involvement in patients with diffuse large B-cell lymphoma (DLBCL) who received rituximab-based therapy. MATERIALS AND METHODS A total of 567 consecutive patients with newly diagnosed DLBCL treated with rituximab-CHOP (RCHOP) between November 2001 and March 2010 were included in the current study. All of the patients underwent a BM study at the initial staging and the clinical characteristics and prognosis of these patients with or without BM involvement were analyzed retrospectively. RESULTS The total cohort included 567 patients. The overall incidence of BM involvement was 8.5%. With a median follow-up duration of 33.2 months (range, 0.1 to 80.7 months) for patients who were alive at the last follow-up, the five-year overall survival (OS) and event-free survival (EFS) rate in patients without BM involvement (76.3% and 67.5%, p<0.001) was statistically higher than that in patients with BM involvement (44.3% and 40.1%, p<0.001). In multivariate analysis, among total patients, BM involvement showed a significant association with OS and EFS. In univariate and multivariate analyses, even among stage IV patients, a significant association with worse EFS was observed in the BM involvement group. CONCLUSION BM involvement at diagnosis affected the survival of patients with DLBCL who received RCHOP. Although use of RCHOP can result in significant improvement of the therapeutic effect of DLBCL, BM involvement is still a negative prognostic factor of DLBCL patients in the era of rituximab.