SURG-54. RECURRENT BRAIN METASTASES (RBM) TREATED WITH SURGICALLY TARGETED RADIATION THERAPY (START): PRELIMINARY SAFETY EVALUATION FROM A MULTI-INSTITUTIONAL PROSPECTIVE REGISTRY

Abstract BACKGROUND Resection and intraoperative brachytherapy for operable recurrent brain metastasis allows for pathologic confirmation of recurrent disease, mass effect relief, and immediate initiation of radiotherapy (RT). In this analysis, we report patterns-of-use and treatment-related adverse events (AEs) for rBM patients treated with Cs-131 collagen tiles, an FDA-cleared intracranial brachytherapy device. METHODS Patients with rBM who underwent resection and surgically-targeted radiation therapy (GammaTile, GT Medical Technologies Inc., Tempe, AZ USA) on a prospectively enrolling phase 4 registry study (NCT04427384) were analyzed. AEs were graded per CTCAE v5.0. RESULTS Between 11/2020 and 2/2024, 56 rBM in 51 consecutive patients underwent STaRT at 19 centers, with 5 patients having 2 metastases implanted concurrently. 44 patients (86%) had prior same-site RT (median interval 14.5 mo, range 3-56). Primary tumor histologies were lung (27), melanoma (8), breast (7), renal (4), colon (2), and “other” (3). Median pre-operative maximum diameter was 3.0 cm (range 1.4-5.7); age 63 (range 28-81); 53% females; KPS median 90 (range 40-100); and median implantation time 3 minutes. 26 patients were implanted at a 1st, 15 at a 2nd, and 10 at ≥ 3rd same-site recurrence (range 1-9). At a median follow-up of 6.2 months (range