Clinicopathologic characteristics and treatment outcome of the addition of rituximab to chemotherapy for CD5-positive in comparison with CD5-negative diffuse large B-cell lymphoma

Background: CD5-positive (CD5+) diffuse large B-cell lymphoma (DLBCL) comprises ∼10% of DLBCLs, and it is associated with poor prognosis. The clinicopathologic characteristics and prognosis of CD5-negative (CD5-) DLBCL and CD5+ DLBCL were compared. Patients and methods: The subjects were 607 DLBCL patients in whom cell surface markers could be analyzed, among 930 consecutive patients registered in the Adult Lymphoma Treatment Study Group between 1998 and 2008.Results: In all, 102 patients (16.8%) had CD5+ DLBCL. Compared with CD5- DLBCL, CD5+ DLBCL was more closely associated with elevated serum lactate dehydrogenase level, advanced stage, poor performance status, extranodal sites, CD10-, BCL-2+, MUM1+, and nongerminal center B-cell type. The 5-year overall survival (OS) rates of CD5+ DLBCL (n = 102) and CD5- DLBCL (n = 505) were 55% and 65%, respectively (P = 0.032), with 5-year progression-free survival (PFS) rates of 52% and 61%, respectively (P = 0.041). In the CD5+ DLBCL patients, the addition of rituximab to chemotherapy significantly improved PFS (4-year PFS, 47.4% versus 62.5%), but not OS (4-year OS, 57.8% versus 63.5%).Conclusions: For CD5+ DLBCL, the addition of rituximab to chemotherapy significantly improved the PFS, but not OS. Therefore, it is thought that a new treatment strategy is necessary for CD5+ DLBCL.