Abstract
For patients with a limited number (<10) of brain metastases (BM), studies increasingly support excellent disease control with stereotactic radiosurgery (SRS) in lieu of whole brain radiotherapy (WBRT), with potential for improved neurocognitive preservation. With increasing disease burden (≥`10 BM), SRS outcomes remain unclear. We identified 97 patients with 10 or more brain metastases who underwent fixed-frame SRS (FFSRS) without WBRT for newly-diagnosed or recurrent BMs at our institution between September 1998 and December 2013. We reviewed dose-volume metrics, treatment-related outcomes of overall survival (OS), treated lesion freedom from progression (FFP), freedom from new metastases (FFNM), and adverse radiation effect (ARE). Among the patient cohort, the median age was 56 (range 17–84) and median KPS 80 (range 40–90). Primary histologies were predominantly breast, lung, and melanoma. Median number of BM per patient was 12 (IQR 11–16). Median total treatment volume was 4.3 cc (IQR 2.3–11.5 cc). Forty-three patients received FFSRS without WBRT as upfront BM radiotherapy and 54 as salvage therapy after prior WBRT, with median OS 7.8 and 8.8 mo, respectively. FFP at 1 year with 95% confidence intervals for upfront vs. salvage FFSRS was 94% (91–96%) vs. 86% (81–90%) by lesion. FFNM at one year for upfront vs. salvage FFSRS was only 9% (2–22%) vs. 14% (4–30%). At progression, 40 patients received additional FFSRS, 20 (21%) had WBRT, and one had partial brain radiotherapy. Median brain and hippocampal volume receiving 8Gy was less than 10% and 1% respectively. Symptomatic ARE was observed in 1% of 1018 treated lesions over the patients’ disease course. Our institutional experience demonstrates excellent local control following FFSRS for patients with 10 or more BM as upfront therapy or at recurrence following prior WBRT. Hippocampal avoidance can be readily achieved and rates of ARE were modest, consistent with prior studies.