• Eun Jung Lee, Hyun-Tai Chung, Hangeul Park, Jin-Wook Kim, Dong Gyu Kim, and Sun Ha Paek.
• 1Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul.
• J. Neurosurg. 2023 Jun 1; 138 (6): 158015901580-1590.

ObjectiveGamma Knife surgery (GKS) is a well-established treatment for benign intracranial meningiomas; however, the dosimetric factors associated with long-term GKS efficacy and safety remain to be elucidated. Using data obtained with at least 10 years of follow-up, the authors aimed 1) to analyze GKS efficacy and safety for the treatment of benign meningiomas confined to non-skull base, nonperioptic supratentorial locations and 2) to determine the radiation dose window that allows for long-term efficacy and safety, namely the minimum dose to achieve long-term local control (LC) and the maximum safe dose to avoid adverse radiation effects (AREs).MethodsA retrospective analysis was performed on patients who underwent GKS for benign meningiomas in the abovementioned location at the authors' institution between 1998 and 2010 and who received follow-up for more than 10 years. The authors meticulously extracted the values of various dosimetric factors by using a dose-volume histogram. Cox proportional hazard regression analyses were performed to investigate the dosimetric factors associated with LC and ARE.ResultsFifty-five patients (male/female ratio 1:4.2) with 68 tumors were enrolled. The median (range) gross target volume and marginal dose were 4.2 (0.2-31.7) cm3 and 14.3 (9-20) Gy, respectively. In total, 23.5% of tumors progressed at an average of 72 months, with 10- and 15-year progression-free survival rates of 80.9% and 73.5%, respectively. In univariate analysis, higher marginal dose, coverage (%), Dmin, D98%, Dmean, D2%, Dmax, and Paddick conformity index were significantly associated with LC. In multivariate analysis, D98% was the significant factor, with a cutoff value of 11 Gy (HR 0.754, p < 0.001). Symptomatic AREs occurred in 7 patients at an average of 7 months after GKS. AREs were significantly associated with the volume of normal tissue irradiated with more than 14 Gy (nV14Gy), with a cutoff value of 0.66 cm3 (HR 2.459, p = 0.002).ConclusionsD98% was a barometer of the minimum required dose associated with long-term LC, and nV14Gy was related to symptomatic AREs. The authors recommend a marginal dose ranging from 11 to 14 Gy to achieve long-term efficacy and safety in patients with non-skull base, nonperioptic benign supratentorial meningiomas, with the assumption of thorough tumor coverage.

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