Early Experience and Perioperative Risk of Gammatile for WHO Grade II Meningioma: Report from a Prospective Multicenter Study

Introduction: 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 including WHO Grade II Meningioma. This study reports early experience utilizing GT in recurrent WHO Grade II Meningioma with a focus on perioperative safety and clinical applications.

Methods: The STaRT Registry (NCT04427384) was queried for all patients receiving GT for WHO Grade II Meningioma from January 2021 to December 2023. Data regarding patient demographics, procedure details, overall survival, recurrence, and adverse events (AEs) were extracted and analyzed.

Results: Sixteen tumors from fourteen patients were included in the analysis. The median age was 52 years (range 24–73), with tumors treated from 10 institutions. Eight patients (57%) had prior fractionated SRS, while 5 patients (36%) had single fraction SRS, and two patients (14%) had WBRT prior to GT placement. The mean diameter of treated meningioma was 3.42cm (range 1.8-9.8). Gross total resection was achieved in 9 patients (64%) at the time of tile implantation. The median follow up was 6 months (range 1-22) with 3 attributed AEs (18.8%), all CTCAE grade 3 AEs. No AEs were reported in the immediate postoperative period (30 days). At 3-month follow-up one patient developed wound dehiscence, requiring surgical intervention. At 1-year follow-up, there was 1 incidence of radiation necrosis, not requiring any intervention. At 15-month follow-up, 1 patient developed subacute lacunar infarct, requiring medical intervention. Local failure (within 1.5 cm of the implant bed) occurred in 2 tumors (12.5%) at 5 months and 18 months, respectively. The overall survival at 22-months is 75%, with death occurring in only two patients during this follow-up period.

Conclusion : GT demonstrates a favorable local control of 87.5% over a less than two year follow up interval accompanied by a safety profile of 18.8% rate of AEs in recurrent WHO Grade II meningioma.