Evolving consolidation patterns and outcomes for a large cohort of patients with primary CNS lymphoma

Consolidation for primary central nervous system lymphoma (PCNSL) after induction chemoimmunotherapy include whole-brain radiotherapy (WBRT; ≤24 Gy reduced-dose [RD], >24 Gy standard-dose) and cytarabine, nonmyeloablative chemotherapy (NMC), or autologous hematopoietic cell transplantation (AHCT). Comparative outcomes are lacking. Outcomes from 1983-2020 were stratified by decade and Memorial Sloan Kettering Cancer Center recursive partitioning analysis (RPA) class. Clinicodemographic associations were analyzed by multinomial logistic regression. Progression-free survival (PFS) and overall survival (OS) were analyzed by proportional hazards. Of 559 patients, 385 (69%) were consolidated. Median follow-up and OS were 7.4 and 5.7 years, respectively. WBRT use declined (61% (1990s) vs 12% (2010s)), whereas AHCT (4% (1990s) vs 32% (2010s)) and NMC (27% (1990s) vs 52% (2010s)) rose. Compared with RPA 1, RPA 2 was more likely to receive NMC. Those with partial response to induction were less likely to receive AHCT (odds ratio, 0.36; P = .02). Among 351 with complete response to consolidation, only receipt of rituximab, methotrexate, procarbazine, and vincristine induction was associated with improved PFS (hazard ratio, 0.5; P = .006). Among RPA 1, median PFS and OS were not reached for AHCT or RD-WBRT, vs 2.5 and 13.0 years, respectively, after NMC. Among RPA class 3, median PFS and OS after RD-WBRT were 4.6 and 10 years, vs 1.7 and 4.4 years after NMC. No significant adjusted survival differences were seen across consolidation strategies. NMC is increasingly used in lieu of RD-WBRT despite a trend toward less favorable PFS. RD-WBRT can be considered in patients ineligible for AHCT.