Comparative survival disparities and outcome in primary vs secondary central nervous system lymphoma (CNSL): A population-based analysis using Surveillance, Epidemiology, and End Results (SEER) program (2000-2022).

e14111 Background: Primary CNSL (PCNSL) is a rare, aggressive B-cell non-Hodgkin lymphoma limited to the CNS, while secondary CNSL (SCNSL) represents CNS involvement from systemic lymphoma. Previous observations focused on CNSL have limited data clinically comparing PSNSL and SCNSL. We aimed to evaluate overall survival and associated factors in patients with PCNSL vs SCNSL using a large population database. Methods: We conducted a retrospective cohort study using the SEER-22 database to identify patients diagnosed with CNSL between 2020-2022. Group comparisons used t-tests or ANOVA for continuous variables, chi-square tests for categorical variables, and Kaplan–Meier survival analysis, with all analyses performed in RStudio 4. 1. 1 and significance deemed as p<0. 05. Results: 14, 964 patients with CNS lymphoma were identified, with 84. 6% PCNSL and 15. 4% SCNSL cases. The overall median age was 65 years (IQR 20), with 52% male, 66% White patients, residing in urban areas (90%) and median household income of 50, 000–75, 000 (52%). Compared with PCNSL, patients with SCNSL were significantly older (72 vs 64 years, p<0. 0001). SCNSL more frequently involved the cerebrum (39% vs 34%) and cerebellum (5. 5% vs 4. 5%), but less commonly affected the nerves (12. 0% vs 12. 5%) and spinal cord (4. 2% vs 5. 1%) (p<0. 05). Disease was predominantly unilateral (95. 8%) in both groups. Chemotherapy (55% vs 56%) and radiotherapy (19% vs 18%) utilization did not differ significantly, with external beam radiation comprising 94. 3% of radiated cases. PCNSL patients were more likely to undergo surgical intervention than SCNSL patients (31. 8% vs 28. 7%; p=0. 0027). Diffuse large B-cell lymphoma was the most common histologic subtype in both PCNSL (70. 1%) and SCNSL (74. 3%). Median overall survival was shorter in SCNSL (1. 64 years) than PCNSL (1. 99 years). Survival improved significantly across diagnostic eras (2000–2005 to 2016–2020; log-rank p<0. 001), while lower income (<50, 000) and rural residence were associated with inferior outcomes (p=0. 028 and p=0. 033). Conclusions: Survival in CNS lymphoma remains poor, with SCNSL associated with worse outcomes compared with PCNSL. Greater understanding of treatment variation and disease differences is needed to optimize therapy and improve patient outcomes. Characteristic PCNSL SCNSL Total p-Value N 12667 2297 14964 Population Distribution 0. 033 Urban 11426 2038 13464 Rural 1241 259 1500 Surgery 0. 0027 Yes 3630 730 4360 No 9037 1567 10604 Months from Diagnosis to Rx (Mean, SD) 0. 31 (0. 86) 0. 27 (0. 65) 0. 30 (0. 83) 0. 0077 Death Status <0. 0001 Dead 8603 1772 10375 Alive 4064 525 4589 Overall Survival (in years, Mean, SD) 1. 99 (2. 85) 1. 64 (2. 31) 1. 93 (2. 77) <0. 0001