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 (CD52) 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 CD52 DLBCL, CD5+ DLBCL was more closely associated with elevated serum lactate dehydrogenase level, advanced stage, poor performance status, extranodal sites, CD102, BCL-2+, MUM1+, and nongerminal center B-cell type. The 5-year overall survival (OS) rates of CD5+ DLBCL (n = 102) and CD52 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.