BACKGROUND: There has been significant improvement in treatment outcomes of primary central nervous system lymphoma (PCNSL) at specialized centers over the past several decades; however, it is unclear if these changes have translated to benefits in the general population. METHODS: In this study, we utilized 2 national databases to examine survival trends over time for PCNSL: the Central Brain Tumor Registry of the United States (CBTRUS, 2000-2013) and 18 registries from the Surveillance, Epidemiology, and End Results program (SEER, 1973-2013). RESULTS: The annual incidence of PCNSL in 2013 was 0.4 per 100000 population (CBTRUS/SEER). Incidence increased from 0.1 per 100000 in the 1970s to 0.4 per 100000 in the 1980s, correlating with an increase in the diagnosis of patients ≥70 years (1973: 0.2 vs 2013: 2.1 [SEER]). Incidence rates differed greatly between young and elderly patients (age 20-29 y: 0.08 vs 70-79 y: 4.32 [CBTRUS]). Even though the median overall survival of all patients doubled from 12.5 months in the 1970s to 26 months in the 2010s, this survival benefit was limited to patients <70 years. Survival in the elderly population has not changed in the last 40 years (6 mo in the 1970s vs 7 mo in the 2010s, P = 0.1). CONCLUSION: The poor outcome seen in the particularly vulnerable elderly patient population highlights the need for clinical trials targeting the elderly in hopes of improving treatment strategies and survival.