Ctni-65. Long Term Results of Resection and Permanent Intracranial Brachytherapy Using Modular, Biocompatible Cesium-131 Implants for Recurrent Aggressive Meningiomas: 5-Year Results From a Prospective Phase 2 Trial

BACKGROUND Management of recurrent, aggressive meningiomas remains problematic. We undertook this analysis to evaluate the efficacy of maximal safe surgical resection (R) plus cesium-131collagen tile brachytherapy (CTBT) in the management of these difficult cases. OBJECTIVE To report the final results from a pre-FDA clearance trial of R plus CTBT (GammaTile, GT Medical Technologies, Tempe, Arizona, USA) for the treatment of recurrent, aggressive meningiomas. METHODS Patients with recurrent aggressive meningiomas were enrolled preoperatively in a prospective, nonrandomized, single-center trial (NCT03088579) between June 2013 and January 2018. Treatment included maximal safe resection and intraoperative CTBT palcement. Local progression (defined as tumor recurrence ≤1.5 cm of the operative bed) was determined on follow-up imaging. Hazard ratios (HR) were utilized to compare the efficacy of R plus CTBT to prior same-site treatment for each case. RESULTS There were 29 recurrent aggressive meningiomas treated in 27 patients. Median age was 66 (range 37-82) years and World Health Organization Grade at the time of R+CTBT was Grade 1 in 1 (3%) patient, Grade 2 in 26 (90%) patients, and Grade 3 in 2 (7%) patients. Prior same-site treatment was R plus radiation therapy (RT) in 76%, 21% R alone, and 3% RT alone. Median radiographic follow-up was 34.8 (0.03-70.9) months. Local control (LC) following R plus CTBT was 79%/73%/48% at 36/48/60 months, compared to 28%/21%/17% with prior treatment (HR=0.14, p=0.0004). Surgically related complications occurred in 4 (13.7%) cases; 1 (3.4%) case of early postoperative infection and delayed onset wound breakdown and infection in 3 cases (10.3%). Symptomatic radiation injury occurred in 4 (13.7%) patients, and all resolved with medical therapy. CONCLUSION Maximal safe resection plus CBCT using a now FDA-cleared device significantly improved LC outcomes with acceptable complication rates in patients with recurrent, aggressive meningiomas when compared with the prior same-site treatments.