GammaKnife radiosurgery for meningiomas in neurofibromatosis type II patients: a systematic review and meta-analysis

Neurofibromatosis type II (NF2) is a genetic disorder marked by the development of multiple CNS tumors, including meningiomas. Managing NF2-associated meningiomas is complex due to the high tumor burden and the need to preserve neurological function. Gamma Knife radiosurgery (GKRS) offers a minimally invasive approach for targeted tumor control, but data on its long-term safety and efficacy in NF2 patients are limited. This meta-analysis assesses the effectiveness of GKRS for NF2 meningiomas, focusing on tumor control, survival outcomes, and adverse effects. This study was conducted according to the PRISMA guidelines. Pubmed (MEDLINE), Embase, Web of Science, and the Cochrane Library databases were systematically searched for studies reporting clinical outcomes of NFII patients with meningiomas treated with GKRS. Data was analyzed using a random-effects model in R Studio. Six studies, comprising 146 patients and a total of 665 meningiomas, met the inclusion criteria. The median age ranged from 32.5 to 40 years, and the median maximum dose administered ranged from 24.5 to 32 Gy. Local progression at the last follow-up was observed in 41 out of 665 tumors (6%; 95% CI 4-9; I²=45%). Five-year overall survival (OS) was 90% (95% CI 79-96; I²=40%). Radiation-induced adverse effects occurred in 22 patients (18%; 95% CI 8-36; I²=70%), of which 20 were transitory. Mortality due to tumor progression was 17% (95% CI 10-28; I²=48%) at the last follow-up, with no reported cases of malignant transformation among treated lesions. These findings suggest that Gamma Knife radiosurgery provides effective tumor control and favorable survival outcomes in neurofibromatosis II patients with meningiomas, with a relatively low rate of local progression and acceptable safety profile.