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

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-year: 56.8% and 10-year: 38.8%). ITC 54.2% (5-year: 48.5%) and OTC 50.5% (5-year: 44.0%). PFS was 56.3% and 30.2% at 5 and 10 years, respectively. DSS remained high at 89.7% (5-year) and 79.7% (10-year), while OS was 79.3% (5-year) and 55.2% (10-year). Independent predictors of LC included recurrent versus 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 occurred in 2.8%. CONCLUSION: Single-fraction stereotactic radiosurgery 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.