Is Fractionated Gamma Knife Radiosurgery a Safe and Effective Treatment Approach for Large-Volume (>10 cm³) Intracranial Meningiomas?

Abstract

Even with great advances in surgery and improved clinical outcome, morbidity and mortality are still high for large-volume intracranial meningiomas (MNGs). Recently, Gamma Knife radiosurgery (GKS) has proven to be a safe and effective treatment for many patients with intracranial MNGs. However, single-session GKS may increase the risk of radiation-induced toxicity for large MNGs. Recently, fractionated GKS (FGKS) has been performed for an increasing number of patients with surgically high-risk and large intracranial tumors. In this study, we report our results on the efficacy and safety of FGKS for large MNGs. The authors performed a retrospective review of 70 patients who underwent GKS for large-volume (>10 cm³) intracranial MNGs between 2004 and 2015, with a minimum follow-up of 12 months. The authors classified these patients into 2 groups of single-session GKS, FGKS. The patients were followed by clinical examination and serial imaging with magnetic resonance imaging. In the single-session GKS group (42 patients), the median tumor volume was 15.2 cm³ (range 10.3-48.3 cm³); the median prescription dose was 12 Gy (range 8-14 Gy), and the median follow-up duration was 57.8 months (range 14.5-128.4 months). In the FGKS group (28 patients), the median tumor volume was 21 cm³ (range 10.2-54.7 cm³), and the median prescription was 7.5 Gy in 2 fractions (range 5-8 Gy), 6 Gy in 3 fractions (range 5-6.5 Gy), and 4.5 Gy in 4 fractions. The median follow-up duration for the FGKS group was 50 months (range 12.5-90.6 months). The overall 5-year tumor control rate was 92.9% in the FGKS group and 88.1% in the single-session GKS group. Fourteen (33.3%) symptomatic complications after single-session GKS were noted, including 5 cases of hemiparesis, 4 of seizure, 3 of peritumoral edema, and 2 of hydrocephalus. Two (7.1%) symptomatic complications after FGKS were noted, including 2 cases of hemiparesis. The FGKS group had higher progression-free survival (PFS) rate at 5 years (92.9% vs. 88.1%), but the differences did not reach statistical significance (P = 0.389). The patients in the FGKS group, however, experienced a lower complication rate compared with patients with a single-session GKS group (P = 0.017, hazard ratio, 5.7:1). When the large-volume (>10 cm³) intracranial MNGs are expected to have high morbidity after microsurgery and for patients that have a poor medical status for surgery, FGKS can be considered an alternative with good tumor control and lower complications rates compared with single-session GKS (P = 0.017).