Single-fraction stereotactic radiosurgery for residual, recurrent, or metastatic intracranial solitary fibrous tumors: an IRRF study toward management guidance

Abstract

Background: Intracranial solitary fibrous tumors (SFTs) are rare, aggressive neoplasms with high local recurrence. This study evaluates the efficacy and prognostic factors of single-fraction stereotactic radiosurgery (SRS).

Methods: This multicenter retrospective study included 107 patients (253 SFTs) treated with single-fraction SRS at 18 centers (1989-2024). We analyzed local control (LC), intracranial tumor control (ITC), overall tumor control (OTC), progression-free survival (PFS), disease-specific survival (DSS), and overall survival (OS). Cox regression identified prognostic factors.

Results: Median follow-up was 33 months. LC was 68.4% (5-yr: 56.8% and 10-yr: 38.8%). ITC 54.2% (5-yr: 48.5%) and OTC 50.5% (5-yr: 44.0%). PFS was 56.3% and 30.2% at 5 and 10 years, respectively. DSS remained high at 89.7% (5-yr) and 79.7% (10-yr), while OS was 79.3% (5-yr) and 55.2% (10-yr). Independent predictors of LC included recurrent vs. metastatic SFTs (HR: 1.96, p = 0.028), margin dose ≤16 Gy (HR: 2.35, p = 0.006), larger tumor volume (HR: 1.05, p < 0.001), and longer diagnosis-to-SRS duration (HR : 1.02, p < 0.001). Older age (HR: 1.03, p = 0.014) and longer resection-to-SRS duration (HR: 1.02, p = 0.018) predicted worse ITC. Age significantly affected OS (HR: 1.06, p < 0.001) and PFS (HR: 1.03, p = 0.037). Longer diagnosis-to-SRS (HR: 1.03, p = 0.002) and resection-to-SRS durations (HR : 1.02, p = 0.030) predicted worse PFS. KPS score >70 predicted better outcomes across ITC, OTC, DSS and OS. Radiation-related adverse effects occured in 2.8%.

Conclusion: SRS offers reasonable tumor control and favorable long-term survival in the adjuvant and salvage setting for patients with residual, recurrent, or metastatic intracranial SFTs. Key prognostic factors included tumor volume, recurrence status, and timing of SRS.