Impact of Systemic and Radiation Therapy on Survival of Primary Central Nervous System Lymphoma

Introduction: Treatment for primary central nervous system lymphoma (PCNSL) includes high-dose methotrexate (HD-MTX)-based systemic therapy. Multiple regimens exist with no clear standard of care. We evaluated the impact of different therapies on PCNSL outcomes at a single institution. Materials and Methods: A total of 95 consecutive patients with PCNSL from 2002 to 2021 were retrospectively reviewed. The overall survival (OS) and progression-free survival (PFS) were estimated by the Kaplan-Meier method. The log-rank test and univariate and multivariable Cox regression analysis were used to evaluate the relationship between clinicopathologic and treatment variables with outcomes. Results: Among the 62 patients treated with definitive systemic therapy, the median age was 58; 71% had a Karnofsky performance status > 70, 49% had a single lesion, 31% received HD-MTX alone, and 61% had HD-MTX + rituximab. The two-year OS and PFS were 64% (95% CI: 49.8-75.0%) and 49% (95% CI: 35.0-60.9%), respectively. On multivariable analysis, the completion of > six cycles of HD-MTX (HR 0.40; 95% CI: 0.21-0.76; p = 0.01) was associated with superior OS, while the use of rituximab was associated with inferior OS (HR 2.82; 95% CI: 1.37-5.83; p = 0.01). There were no significant associations between the OS and PFS with temozolomide, the extent of surgical resection, radiation, or the size or number of initial lesions (all p > 0.05). Discussion: Innovation is needed to improve the outcomes for patients with PCNSL.