Real world experience of primary central nervous system lymphoma in a multi‐ethnic asian cohort

Introduction: Primary Central Nervous System Lymphoma (PCNSL) is a rare and intractable disease with a dismal prognosis. There is a paucity of data on Asian patients’ outcome, we aimed to review the clinicopathologic characteristics and prognostic factors influencing survival patterns of Asian patients with PCNSL. Methods: A retrospective review of adult PCNSL patients treated with frontline chemotherapy (ChT) consisting of methotrexate, vincristine, procarbazine (MVP) with or without rituximab (R-MVP), at two tertiary cancer centres in Singapore, between year 2000 and 2019 was conducted. We recorded data on demographics, ChT regimen, radiotherapy doses, treatment response and survival outcomes. Overall survival (OS) and progression-free survival (PFS) were calculated using the Kaplan-Meier method. Univariate associations were derived using a Cox regression model. All statistical analyses were performed using R. Results: A total of 127 patients were analysed. Seventy-five (59%) were male and median age at diagnosis was 59 years (range: 20–78). Ethnic subgroups included 86 (67.7%) Chinese, 27 (21.3%) Malay, 7 (5.5%) Indian and 7 (5.5%) others. Median follow-up duration was 5.9 years (IQR 3.82 to 8.79 years). Most patients (n = 116, 91%) had ECOG performance status of 0-2. We observed that deep brain structure involvement was common (n = 99, 78%). Of the 80% patients with data on cerebrospinal fluid and intraocular involvements, these events were rare at 13.4% and 16.5% respectively. Classification by cell-of-origin revealed that 49.6% were of non-germinal centre (GC) subtype and 13.4% were GC subtype, while the rest were unknown. All patients received the MVP induction chemotherapy regimen with (40.9%) or without (59.1%) rituximab. Consolidation radiotherapy was administered to 100 patients (78.7%), while consolidation chemotherapy using cytarabine was administered to 69 patients (54.3%). None of the patients underwent upfront stem cell transplant. Approximately half the cohort (48.8%) received at least a single dose of intrathecal methotrexate. The median systemic methotrexate dose was 2.5 g/m2 and median radiotherapy dose was 36 Gy. The best overall treatment response rate was 94%, with 77% attaining complete response. Median OS was 4.5 years and median PFS was 3.6 years. 2-year PFS was 63.4% and 2-year OS was 76.9%. On univariate analysis, GC subtype was associated with improved PFS (HR = 0.13, 95% CI 0.03–0.55, p = 0.006) and OS (HR = 0.17, 95% CI 0.04-0.71, p = 0.015). Addition of rituximab to ChT and radiotherapy conferred survival advantage though this was not statistically significant. Keywords: aggressive B-cell non-Hodgkin lymphoma, extranodal non-Hodgkin lymphoma No conflicts of interests pertinent to the abstract.