BACKGROUND AND OBJECTIVES: Stereotactic radiosurgery (SRS) has been increasingly employed in the multimodal management of primary central nervous system lymphoma. Here, we evaluate the outcomes of SRS for the treatment of primary central nervous system lymphoma through a multicenter, international cohort study. METHODS: A multicenter, retrospective cohort study was conducted through the International Radiosurgery Research Foundation. Subgroups were defined according to treatment setting: up-front (primary treatment), boost (SRS after consolidative chemotherapy with or without whole-brain radiotherapy), and relapsed/refractory (recurrent/progressive disease after first-line therapy). The primary end point was local tumor control. Time-to-event analysis was conducted using the Kaplan-Meier method. Variables associated with local control were assessed using the Cox proportional hazard modeling. RESULTS: Fifty-four patients with 127 tumor sites were included in this analysis. Actuarial 12-month local and distant control rates for the entire cohort were 75.7% and 63.7%, respectively, with a median overall survival (OS) of 18 months (range: 1-176). Actuarial 12-month local control rates were significantly different at 95.6%, 78.3%, and 42.1% ( P 27 cm 3 (hazard ratio: 2.5, P = .04). CONCLUSION: SRS shows promising local tumor control rates for up-front and relapsed cohorts. Despite this, distant tumor progression limits total tumor control and may adversely affect OS.
Kite et al. (Wed,) studied this question.