Effect of high-dose delivery on the attachment of meningiomas in Gamma Knife surgery: a retrospective study.

Abstract

Meningiomas have vascular supply from the tumor attachment on the dura mater. Gamma Knife radiosurgery (GKS) is known to have a vascular obliterating effect. This study aims to determine the benefits of high-dose irradiation to the tumor attachment compared to conventional dose planning in the long-term control of tumor growth with GKS. Two different dose plannings were retrospectively compared in 75 patients with meningioma treated with GKS as a primary treatment. Forty-three patients were irradiated over 20 Gy to the tumor attachment. The remaining 32 patients were treated with conventional-dose planning. Tumor growth control, reduction of enhancement on the gadolinium-enhanced magnetic resonance imaging (MRI), and neurological status were retrospectively assessed. The maximum dose on the tumor attachment was significantly higher in the high-dose group (23 Gy) than in the conventional group (16 Gy). The tumor margin was irradiated with the median of the 50% isodose line in both groups. The prescription doses resulted in 14 Gy and 12 Gy, respectively. The tumor control rate achieved 91% in both groups during the median follow-up period of 54 months. A decrease of enhancement on follow-up MRI was noted in one patient in each group. Kaplan-Meier analysis revealed no statistical difference in the progression-free survival between the two groups. The number of patients with improved neurological status showed no statistical difference. No obvious benefit of high-dose irradiation to the tumor attachment and margin was found in tumor control and neurological status in the long term.