RADT-65. SURGICALLY TARGETED RADIATION THERAPY (START) FOR RECURRENT MENINGIOMA: INITIAL REPORT ON A MULTI-INSTITUTIONAL PROSPECTIVE STUDY

Abstract BACKGROUND The management of recurrent meningioma is challenging. Multimodality treatments, including combining resection with implantable collagen-tile cesium-131 brachytherapy (STaRT) (GammaTile®, GT Medical Technologies, Tempe, AZ, USA), may be a good therapeutic option. OBJECTIVE To assess the efficacy of resection and STaRT for management of aggressive recurrent meningioma on a prospective, multi-center observational study. METHODS The first 44 consecutive patients with recurrent meningioma enrolled on the observational registry (NCT04427384) were assessed at 21 centers for patient demographics, tumor characteristics, local control (LC), and adverse events (AEs). These data were collected from 1/28/2021-5/16/2025. RESULTS Patients with recurrent meningioma (six World Health Organization Grade 1, twenty-one Grade 2, and seventeen Grade 3) underwent resection and STaRT. Expressed a medians, age was 61 years (24-83), follow-up was 11.2 months (0.2-36.1), and maximum preoperative tumor diameter was 4.3 cm (1.2-9.8), 90.5% had prior radiation, with a median interval of 38.4 months (3.4-126.3). By Grade, LC at 6, 12, and 15 months were 83.3%, 83.3%, and 66.7% for Grade 1; 100.0%, 68.6%, and 68.6% for Grade 2; and 92.9%, 76.0%, and 63.3% for Grade 3. For all Grades combined, LC at 6, 12, and 15 months were 94.4%, 78.3%, and 67.0%. Progression-free survival (PFS) by grade at 6, 12, and 15 months were 83.3%, 83.3%, 66.7% for Grade 1; 84.6%, 52.7%, and 52.7% for Grade 2; and 60.0%, 20.0%, and 13.3% for Grade 3. For all Grades combined, PFS at 6, 12, and 15 months were 74.6%, 45.5%, and 37.1%. Median overall survival has not been reached. Seven patients (15.9%) had eight Grade ≥3 AEs (3 infection/dehiscence, 2 each hematoma and edema/necrosis [1 radiation-related], and 1 seizure). CONCLUSION This report from 21 centers demonstrates that resection plus STaRT for aggressive, recurrent meningiomas resulted in encouraging LC and low AE rate.