Outcomes and relapse patterns in primary central nervous system lymphoma: Longitudinal analysis of 559 patients diagnosed from 1983 to 2020

Abstract Background Contemporary outcomes and relapse patterns in primary CNS lymphoma (PCNSL) are lacking. We analyzed factors associated with relapse in a large cohort with extensive follow-up. Methods T1-post-contrast-enhancing disease was characterized in immunocompetent PCNSL (diffuse large B-cell) patients from 1983 to 2020. Patients were stratified by response to induction and consolidation (complete/unconfirmed [CR/CRu], partial, stable, progression [POD]). Refractory was POD during (or relapse ≤3 months of) induction. Initial relapse site was categorized as local (involving/adjacent to baseline), distant intraparenchymal, leptomeningeal, or other. Progression-free (PFS) and overall survival (OS) were assessed with proportional hazards. Cumulative incidence with competing risks was used to assess local relapse. Results Median follow-up was 7.4 years (N = 559). Most (321, 57%) were recursive partitioning analysis class 2 (age ≥50, Karnosfky Performance Status [KPS] ≥70). Most had supratentorial (420, 81%), multifocal (274, 53%), bilateral (224, 43%), and deep structure involvement (314, 56%). Nearly all received methotrexate-based induction (532, 95%). There was no difference in PFS or OS from consolidation based on initial response to induction (CR/CRu vs PR) in patients who ultimately achieved a CR/CRu to consolidation. PFS at 1-, 5 years for 351 patients with CR/CRu to consolidation was 80% (95% confidence interval [95% CI]: 76%–84%) and 46% (95% CI: 41%–53%), respectively; 1-year cumulative incidence of local versus nonlocal relapse was 1.8% versus 15%, respectively. For 97 refractory patients, 1-year cumulative incidence of local versus nonlocal relapse was 57% versus 42%, respectively. Deep structure involvement (HR 1.89, 95% CI: 1.10%–3.27%) was associated with local relapse in refractory patients. Conclusions We report the first comprehensive relapse patterns in a large PCNSL cohort. While relapses post-CR to consolidation are typically distant and unpredictable, refractory patients had a relatively high incidence of local relapse. These findings can help optimize multimodality therapy for this highest-risk population.