199 Gamma Knife Radiosurgery to Treat Neurofibromatosis Type 2-Associated Meningiomas: A 35 Year Experience and Paradigm for Future Treatment

Abstract

INTRODUCTION: Management of neurofibromatosis type 2 (NF2)-associated meningiomas remains a case-by-case basis, and treatment options vary. METHODS: Forty-nine patients (22 male, 44.90%) with 213 NF2-associated meningiomas treated with SRS between 1987 and 2022 were retrospectively reviewed. The median age at SRS was 56 (range: 20-79) years. Twenty-nine (59.18%) patients had pre-SRS surgical resection, and 7 (14.29%) had prior radiotherapy. The median number of meningiomas per patient was 2 (range: 1-17), the median margin dose was 13 (range: 9-16) Gy, and the median cumulative tumor volume per patient was 8.30 (range: 0.10-74.26) cm3. RESULTS: Nine patients (18.37%) had local tumor progression. The 1- and 5-year local tumor control rates were 100% and 90.54%, respectively. Tumor volume < 8.30 cm3 was associated with better local tumor control (p = 0.02, HR: 1.06, 95% CI: 1.01-1.12) on multivariate analysis. Twenty-five patients (51.02%) had detection of new growing tumors (DNGT). The 1- and 5-year DNGT rates were 78.05% and 47.38%, respectively. On multivariate analysis, >2 meningiomas at SRS presentation per patient (p = 0.01, HR: 1.09, 95% CI: 1.02-1.17) was significantly associated with DNGT. Neurological symptoms improved in 20 patients (40.82%), remained stable in 28 patients (57.14%), and worsened in 1 (2.04%) patient at a median follow-up time of 81 (range: 6–267) months after SRS. Seventeen (34.69%) patients were deceased at last follow-up, and 4 patients expired due to intracranial disease progression. Two (4.08%) patients developed transient adverse radiation effects; no patients developed secondary malignancies. CONCLUSIONS: Single-session SRS can effectively be used to control tumor progression and improve neurological symptoms in NF2-associated meningioma patients while limiting adverse radiation effects.