Single-fraction Gamma Knife radiosurgery for pineal region meningiomas: a retrospective single-center cohort of 44 patients

Abstract

Purpose To evaluate the long-term efficacy and safety of single-fraction Gamma Knife radiosurgery (GKRS) for pineal region meningiomas (PMs) and to clarify its role as both a primary and adjuvant treatment strategy for this anatomically challenging tumor location. Methods This single-center retrospective cohort study included 44 consecutive adults with PMs treated with single-fraction GKRS. Diagnosis was established histopathologically after prior surgery or by predefined MRI criteria with consensus neuroradiological review. Tumor response was assessed volumetrically on serial contrast-enhanced MRI, with regression, stability, and progression defined as ≥ 20% decrease, < 20% change, and ≥ 20% increase in tumor volume, respectively. Local control (LC), progression-free survival (PFS), overall survival (OS), adverse radiation effects (AREs), and Karnofsky Performance Scale (KPS) outcomes were analyzed. Results Median clinical and radiological follow-up were 90 and 88 months, respectively. At last radiological follow-up, LC was achieved in 42 of 44 patients (95.5%), including regression in 13 (29.5%) and stability in 29 (65.9%). Kaplan-Meier LC rates were 100% at 2 years, 97.1% at 5 years, and 86.3% at 10 years. PFS rates were 100%, 94.1%, and 72.6% at 2, 5, and 10 years, respectively. AREs occurred in 3 patients (6.8%), all without permanent sequelae. KPS remained stable or improved in all patients. Conclusion Single-fraction GKRS provides durable tumor control with low toxicity and preserved neurological function in PMs, supporting its use as a primary treatment strategy in selected patients. Preliminary adjuvant results are encouraging but require validation in larger cohorts.