# Clinical Characteristics and Prognosis of Primary Central Nervous System Lymphoma: A Retrospective Analysis

## TL;DR

A study of 140 PCNSL patients found that a specific methotrexate-based treatment combined with stem cell transplantation improved survival rates, but relapse remains a challenge.

## Contribution

Demonstrates the effectiveness of R-MT induction and ASCT consolidation in improving PCNSL survival with extended follow-up data.

## Key findings

- R-MT regimen achieved 75% remission in PCNSL patients.
- 5-year overall survival reached 60.8% with ASCT consolidation.
- No survival plateau was observed, indicating ongoing relapse risk.

## Abstract

Primary central nervous system lymphoma (PCNSL) is a rare extranodal lymphoma with poor prognosis due to high relapse rates and a lack of standardized treatment. This retrospective analysis of 140 immunocompetent diffuse large B-cell PCNSL patients (treated between 2014 and 2024) shows that methotrexate-based induction therapy (notably the rituximab–methotrexate–temozolomide (R-MT) regimen) achieved 75% remission, and consolidation therapy (predominantly autologous stem cell transplantation) improved survival: 5-year overall survival reached 60.8% after a median 5.3-year follow-up. No survival plateau was observed, highlighting the need to standardize PCNSL treatment strategies.

Background: Primary central nervous system lymphoma (PCNSL) is a rare extranodal lymphoma characterized by a poor prognosis due to high relapse rates and a lack of standardized treatment. This study aimed to evaluate the impact of induction/consolidation therapy on long-term survival and to provide extended follow-up data. Methods: In this retrospective analysis, 140 immunocompetent patients with diffuse large B-cell PCNSL (DLBCL-PCNSL) treated at two centers between 2014 and 2024 were enrolled. Treatment efficacy was assessed based on baseline characteristics, therapeutic regimens, and treatment response. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan–Meier method, and prognostic factors were identified using multivariate Cox proportional hazards regression models. Results: With a median follow-up of 5.3 years (range: 0.1–11.0 years), the 2- and 5-year PFS rates were 50.4% (95% CI: 42.1–60.2) and 34.1% (95% CI: 25.5–45.0), respectively, while the corresponding OS rates were 85.3% (95% CI: 79.4–91.6) and 60.8% (95% CI: 52.0–71.1). No survival plateau was observed. Among patients, 94% received methotrexate-based induction therapy: 94 received rituximab–methotrexate–temozolomide (R-MT) and 17 received MT alone, with 2-year PFS rates of 57.7% and 39.7%, respectively. Overall, 75% of patients achieved remission (CR/CRu/PR) after induction, and among these, 55% underwent consolidation therapy, predominantly autologous stem cell transplantation (ASCT, 90%) or whole-brain radiotherapy (10%). Patients receiving ASCT exhibited superior survival outcomes compared to those who did not. Conclusions: R-MT induction combined with ASCT consolidation is associated with improved survival in PCNSL, although relapse risk remains substantial. Outcomes remain poor in refractory subgroups, highlighting the need for novel therapeutic strategies.