P14.23.b Clinical Aspects and Management of CNS Solitary Fibrous Tumors: A Case-Based Review

BACKGROUND Central nervous system (CNS) solitary fibrous tumors (SFT)/hemangiopericytoma is a relatively rare soft tissue vascular tumor. It is widely recognized as an aggressive disease with high recurrence rates. The best treatment approach is still debated, especially in recurrent disease, as well as the best protocol for systemic surveillance. MATERIAL AND METHODS We conducted a single center retrospective study exploring demographics, treatment patterns, progression free survival (PFS) and overall survival (OS) in patients (pts) diagnosed with CNS SFT/hemangiopericytomas in a portuguese oncological center. IBM SPSS Statistics version 23 was used for analyzing procedures. RESULTS Fourteen patients were diagnosed with SFT between September 2008 and October 2024. The median age was 59.5 years old, 57.1% (n=8) were female. Regarding the histological WHO tumor grading score, 50.0% were grade 2 (n=7), 35.7% were grade 3 (n=5) and 14.3% were grade 1 (n=2). The lesions were most commonly supratentorial - 9 pts (64.3%), followed by 4 (28.6%) in the posterior cranial fossa and 1 (7.1%) in the cervical spine. All patients were submitted to surgical resection - 64.3% (n=9) gross total resection (GTR) and 35.7% (n=5) partial resection. The majority, 85.7% (n=12), was submitted to adjuvant focal radiotherapy (RT) - 66.7% after the first resection (n=8) and 33.3% after surgical reintervention on disease recurrence (n=4). Of the patients who were not irradiated, one died shortly after diagnosis and the other has a grade 1 SFT with a short follow-up period. Disease relapse occurred in 57.1% (n=8) - 35.7% (n=5) locoregional recurrence and 35.7% (n=5) systemic disease; 2 pts had both. Among the patients who relapsed, 75% of pts had previous GTR (n=6). In the 6 pts without metastasis or recurrence, half had GTR and the other half had partial resection. Systemic disease occurred in 3 pts with GTR and in 2 pts partial resection. Palliative systemic therapy was administered to 4 patients with chemotherapy, tyrosine-kinase inhibitors and/or immunotherapy. Three of these patients had progressive therapeutic escalation that varied between dacarbazine (n=3), temozolamide and bevacizumab (n=2), pembrolizumab (n=2), doxorubicine (n=1) and trabectedine (n=1). The median follow-up time was 84.5 months (range 1-158 months). Currently, a total of 7 pts (50.0%) are still alive. The median PFS was 72 months (95% CI, 53-91 months) with a PFS rate at 24 months of 90.9%. The median OS was 109 months (95% CI 84-134 months), with an OS rate at 24 months of 92.9%. CONCLUSION CNS STFs manifest with heterogeneous behavior. As described in the literature, recurrent and metastatic lesions can occur despite gross total resection followed by radiotherapy. Further studies with bigger cohorts are needed to establish standardized treatment options specially for recurrent or systemic disease.