Performance status, comorbidities, and cycles of methotrexate exert the greatest influence on outcomes of primary and secondary CNS lymphomas: the Lexington experience

Primary central nervous system lymphoma (PCNSL) occurs primarily in older patients and has a worse prognosis than other extranodal lymphomas. Contemporary treatment is based on high-dose methotrexate (HD-MTX), which crosses the blood-brain barrier. Secondary CNS lymphoma (SCNSL) can occur concomitantly with systemic lymphoma or later at relapse and generally has a dismal outcome. We reviewed disease characteristics and outcomes of 103 patients (44 PCNSL and 59 SCNSL) treated at our center between 2015 and 2020. Median ages at diagnosis were 64 and 62 years, respectively. In both groups, diffuse large B cell lymphoma (DLBCL) was the major histologic type; in SCNSL, other types were also seen. SCNSL, in contrast with PCNSL, manifested with smaller tumors or cerebrospinal fluid positivity. For SCNSL the mean interval to brain involvement was 18 months (0-138). The overall survival had a trend to worse in SCNSL; median survival 11 months versus 61 months in PCNSL (p = 0.089). Progression-free survival was similar in both groups. A significant proportion of SCNSL patients with poor performance status could not obtain CNS-directed treatments. The strongest predictor of poor outcome was ECOG performance status 2 + at diagnosis for both groups. Charlson comorbidity index was predictive only for the PCNSL cohort. Tumor size was not prognostic for survival. The number of HD-MTX cycles correlated with survival, whereas the regimen itself and average cumulative dose of methotrexate did not play a role. Our study is in line with the recent literature and confirms ongoing challenges. We discuss how the outcomes of CNS lymphomas can be improved.

Automated summary

Primary central nervous system lymphoma (PCNSL) and secondary central nervous system lymphoma (SCNSL) have different characteristics and outcomes. PCNSL occurs primarily in older patients and has a better prognosis, while SCNSL can occur concomitantly with systemic lymphoma or later at relapse and generally has a worse prognosis. The treatment strategies for both types are also different.