Single fraction stereotactic radiosurgery (SRS) alone versus surgical resection and SRS boost for large brain metastases: A multi-institutional analysis.

2076Background: SRS dose is typically limited by brain metastasis (BM) size. Any benefit for the addition of surgery to SRS for large BM in patients (pts) with oligometastatic brain disease is not well characterized. Methods: Large BM was defined as ≥ 4 cc (2 cm diameter) prior to the study. The records of consecutive pts treated with single fraction SRS alone or surgery with either pre-operative (pre-SRS) or post-operative SRS (post-SRS [collectively SRS boost]) between 2005 - 2013 from 2 institutions were reviewed. Pre-SRS dose was 20% reduced compared to standard SRS dosing, with planned resection within 48 hours. Overall survival (OS) analysis used the Kaplan-Meier method. Otherwise, cumulative incidence with competing risk was used. Results: Overall, 250 pts with 260 treated large BM were included, of which 66 were treated with SRS alone and 194 with surgery and SRS boost (65 pre-SRS, 129 post-SRS). Median imaging follow-up period was 29 months for alive pts. Groups were well balanced except for lesi...