Radiosurgery for central nervous system ependymomas: a systematic review and meta-analysis

Ependymomas, rare malignant central nervous system (CNS) lesions (2-6% of primary CNS tumors), are typically treated with maximal safe resection followed by fractionated radiation therapy. Stereotactic radiosurgery (SRS) has emerged as an alternative, particularly in recurrent or residual cases. This study evaluates the safety and efficacy of SRS for CNS ependymomas, while also identifying key prognostic factors.

A systematic search was conducted to identify studies that evaluated the efficacy and safety of SRS in WHO Grade 2/3 CNS ependymoma patients. Random-effect meta-analysis was employed.

Fourteen studies with 298 patients and 496 lesions were included. Our meta-analysis demonstrated an overall local tumor control (LTC) rate of 72% (95% CI: 65-79%). LTC rates at 1, 3, and 5 years were 83% (95% CI: 76-88%), 72% (95% CI: 64-78%), and 69% (95% CI: 61-76%), respectively. Progression-free survival (PFS) rates at 1, 3, and 5 years were estimated at 67% (95% CI: 50-80%), 56% (95% CI: 48-64%), and 51% (95% CI: 39-63%), respectively. Additionally, the 5-year overall survival (OS) rate was 58% (95% CI: 48-67%). The incidence of adverse radiation events (ARE) was 20% (95% CI: 12-31%). Meta-regression showed older age correlated with improved tumor control (P = 0.02) and lower ARE (P = 0.06) and radionecrosis rates (P < 0.01), while larger tumor volumes (P = 0.03) and anaplastic histology (P = 0.01) were associated with poorer PFS.

SRS is a reasonably valuable therapeutic option in the multimodal management of WHO Grade 2/3 CNS ependymomas, especially for individuals with inoperable, recurrent, or residual lesions. Key patient and tumor characteristics have been analyzed to determine factors potentially impacting treatment outcomes.