Central nervous system relapse in patients with diffuse large B cell lymphoma: analysis of the risk factors and proposal of a new prognostic model.

Central nervous system (CNS) relapse in patients with diffuse large B cell lymphoma (DLBCL) is an uncommon event, and the outcome of patients with CNS relapse is poor. However, no reliable prediction models for CNS relapse have been developed. We retrospectively analyzed consecutive de novo DLBCL patients referred to our department between September 2004 and August 2015 and treated with R-CHOP or R-CHOP-like regimens. Of 413 patients analyzed in this study, a total of 27 patients (6.5 %) eventually developed CNS relapse. The 5-year probability of CNS relapse was 8.4 %. The median time from diagnosis of DLBCL to CNS relapse was 15 months, and the median survival after CNS relapse was 7 months. In univariate analysis, the risk factors significantly associated with CNS relapse were Ann Arbor stage 3 or 4, albumin level <3.2 mg/L, number of extranodal sites >1, and involvement of retroperitoneal lymph node. We developed a new prognostic model consisting of these four factors. The 5-year probability of CNS relapse was significantly higher in patients with at least three of these four factors than in those with two or fewer factors (26.4 vs. 3.0 %, P < 0.001). Using this model, we evaluated the incidence and the risk factors of CNS relapse in DLBCL patients. The new risk model consisting of the four factors demonstrated good risk stratification for CNS relapse, and could help to identify high-risk patients for whom CNS prophylaxis is warranted.