Autologous stem cell transplantation (ASCT) versus whole brain radiation (WBRT) as a consolidation therapy in primary CNS lymphoma (PCNSL): A nationwide analysis.

Abstract

2062 Background: High dose methotrexate-based regimens remain the most effective treatment against PCNSL but optimal consolidative strategy has yet to be determined. There is lack of high scale clinical trials comparing WBRT versus ASCT as consolidation therapy. Only two phase II randomized clinical trials (PRECIS and IELSG 32) have addressed this question. In this comprehensive national cancer database (NCDB) analysis, we examine the effect of WBRT versus ASCT on survival in PCNSL, we also sought to investigate clinical and socioeconomic predictors of treatment selection Methods: We conducted a retrospective cohort analysis using de-identified data accessed from the NCDB. The NCDB provided records of 16579 patients diagnosed with PCNSL between 2004 and 2016. We excluded patients who tested positive for HIV, and those who started chemotherapy > 120 days or started radiation > 365 days since diagnosis, to account for immortal time bias. Patients were divided into two treatment groups based on consolidation therapy: ASCT and WBRT. Multivariable regression models were used to analyze predictors of treatment selection. To account for variable baseline characteristics, we used propensity score weighting methodology. Survival estimates were calculated using the Kaplan-Meier and Cox proportional hazard regression methods Results: We identified 1620 patients with PCNSL who fulfilled the inclusion criteria. ASCT and WBRT were received by 197 patients and 1423 patients, respectively (Table). On multivariable analysis, increased age decreased the odds of receiving ASCT (OR 0.997, CI: 0.996-0.999, P <.001). Patients live in rural areas (OR 1.174, CI: 1.051-1.312, P=.005), those with higher education (OR 1.089, CI: 1.020-1.163, P=.01), and those who live further from the treating facility (OR 1.001, CI: 1.001-1.001, P<.001) received more ASCT. With a median follow up duration of 27.8 months, adjusted-median OS was 91.4 months and not reached for WBRT and ASCT groups, respectively (log-rank P<.001). Adjusted 3-year OS was 82% and 67% in ASCT and WBRT, respectively (HR: 0.43, CI: 0.29-0.64, P<.001) Conclusions: Consolidation with ASCT had improved OS compared with WBRT. There is a trend toward increased ASCT use and decreased WBRT use over the study period. We found clinical and socioeconomic factors that affected treatment selection.[Table: see text]