LAUSR

OBJECTIVE Convexity meningiomas are common tumors requiring treatment in neurofibromatosis type-2 (NF-2) patients. Although different therapeutic options are reasonably characterized in sporadic convexity meningioma, much less is known about these lesions in NF-2 patients, despite their distinct biology and need for multiple treatments. We analyzed the value of Gamma Knife radiosurgery (GKRS) as definitive treatment for convexity meningiomas in NF-2 patients. METHODS We performed an international multicenter retrospective study approved by the International Radiosurgery Research Foundation. NF-2 patients, with at least one convexity meningioma and 6-month follow-up after primary GKRS, were included in this study. RESULTS Eighteen NF-2 patients met inclusion criteria. A total of 120 convexity meningiomas [media, 0.66 cc (0.10-21.20 cc)] were included in our analysis. The median follow-up time after initial GKRS was 15.6 years (0.6-25.5 years). Median age at GKRS was 32.5 years (16-53 years). The median number of meningiomas per patient was 13 (1-27), and median number of convexity lesions receiving GKRS per patient was 3.5 (1-27). One case of tumor progression was reported 24 years after radiosurgery, leading to actuarial progression free survival (PFS) rates of 100% at 2-, 5- and 10-years. No malignant transformation or death due to meningioma or radiosurgery was registered. CONCLUSION GKRS is safe and effective in the upfront treatment of small to medium size convexity meningiomas in NF-2 patients. Despite the concerns about their particular mutational burden, no malignant transformation presented after treatment. GKRS represents a minimally invasive option offering long-term tumor control to this specific group of patients.