Intracranial Solitary Fibrous Tumor/Hemangiopericytoma Treated with Microsurgical Resection: Retrospective Cohort Analysis of a Single-Center Experience.

Objective: To provide benchmarks for further studies of solitary fibrous tumor/hemangiopericytoma (SFT/HPC) of the central nervous system (CNS), we investigated the association of baseline demographic, clinico-pathologic, and treatment factors with outcomes in those treated at our center. Methods: We conducted a retrospective, cohort analysis of patients treated for SFT/HPC at the University of Washington 1990-2020. Kaplan-Meier and univariable Cox analyses assessed relationships between baseline variables and local or global CNS recurrence, extraneural recurrence, progression-free survival (PFS) and overall survival (OS). Results: Among 34 eligible patients, median duration of follow-up was 79 months (range 13-318 months). Local and global CNS recurrence occurred at a median of 81 m (95% CI 48-151) and 81 m (95% CI 47-112), respectively. Extraneural metastases occurred at a median 248 m (95% CI 180-Not Reached) and only in grade 3 tumors. Median PFS and OS were 76 months (95% CI: 47-109 months) and 210 months (95% CI 131-306 months), respectively. Univariable Cox analyses showed that age at diagnosis was associated with local (p = 0.01) and global CNS relapse (p = 0.01), and PFS (p = 0.03). Gross total resection was associated with decreased local or global CNS relapse (p = 0.02) and improved PFS (p = 0.03); peri-operative radiation was associated with decreased local CNS relapse (p = 0.02). Conclusion: Following microsurgical resection of SFT/HPC, CNS relapse is common and associated with age, extent of resection, and adjuvant radiation. Extraneural relapse occurs in some patients. Delayed time-to-initial relapse justifies prolonged surveillance, but optimal approaches have not been defined.