Early experience and perioperative risk of GammaTile for upfront brain metastases: Report from a prospective multicenter study.

Background: GammaTile (GT), a form of brachytherapy utilizing cesium-131 seeds in a bioresorbable collagen tile, has gained popularity for the treatment of recurrent intracranial tumors and more recently for newly diagnosed metastases. This study reports early experience utilizing GT in upfront brain metastases with a focus on clinical applications and perioperative safety. Methods: The STaRT Registry (NCT04427384) was queried for all patients receiving GT for upfront metastases from August 2021 to August 2023. Data regarding patient demographics, procedure details, and adverse events (AEs) were extracted and analyzed. Results: Twenty-eight patients, median age 65 years (range 28-81), with 30 treated metastases were reported from 6 institutions. Patients had 2.8 metastases on average (range 1-15) at the time of surgery; however, most patients had a single metastasis (60.7%). The mean diameter of treated metastases was 3.4 cm (range 1.5-4.7). A median of 4.0 tiles (range 1-10) were used per tumor. The median follow-up was 3.0 months (range 1.0-11.2) with 6 attributed AEs (21.4%), including 1 grade ≥ 3 (infection). In the immediate postoperative period (<14 days), 2 patients reported pain or headache, and 1 reported facial edema. One patient developed seizures on postoperative day 8 requiring medication. At 1-month follow-up, there was 1 superficial wound infection, in a previously colonized patient, requiring surgical intervention without explantation of tiles. At 3-month follow-up, 1 patient reported facial pain not requiring treatment. There were no symptomatic hematomas. Conclusions: GT demonstrates a favorable safety profile in upfront brain metastases with a 3.6% rate of serious AEs (grade ≥ 3) within 90 days of the procedure.