P09.12.a Outcomes in Solitary Fibrous Tumors With Multimodality Managment in a Specialised Neuro-Oncology Practice in India

BACKGROUND Solitary fibrous tumours (SFT) of the central nervous system (CNS), previously known as hemangiopericytomas (HPC), are rare mesenchymal neoplasms characterized by inversions at 12q13, fusing the NAB-2 and STAT-6 genes, leading to nuclear expression of STAT-6 and its consequent detection on immunohistochemistry. The World Health Organization classification defines three grades of SFT/HPC, with higher grade associated with worse outcomes. Maximal safe resection is the mainstay of treatment, and adjuvant radiotherapy (RT) is often added for high-grade or residual disease. However, due to the rarity of SFT, the impact of these factors on long-term outcomes remains unclear. MATERIAL AND METHODS We performed a retrospective review of all patients with CNS SFT treated at our centre from 2003-2020. Clinical characteristics, treatment details, and outcomes were collected from records. OS and PFS were estimated by Kaplan-Meier analysis, and associations of prognostic factors (tumour grade, extent of resection) with outcomes were evaluated using log-rank tests and Cox regression. A subgroup analysis on the basis of preceding literature was also done based on three risk groups: low risk (Grade 1, any extent of resection, or Grade 2 with gross total resection), intermediate risk (Grade 2 with biopsy or subtotal resection), and high risk (Grade 3, any extent of resection). RESULTS Eighty-two patients were included. The median age was 41 years, and 66% were male. Most tumours were intracranial (97.5%, largely supratentorial) and 93% were WHO grade II or III. Near Total Resection and Gross Total Resection was achieved in 45% and 38% patients respectively, and 75% of patients received postoperative RT (PORT). At a median follow-up of 48 months, 5-year PFS was 54% and 5-year OS was 89%. Neither tumour grade nor extent of resection significantly influenced PFS or OS. In subgroup analysis of 52 patients receiving PORT, no significant difference in outcomes was seen between intermediate- and high-risk groups. CONCLUSION Patients with CNS SFT/HPC treated with surgery and adjuvant therapy achieved favourable long-term outcomes in our series. PORT improves high-risk patient outcomes to levels comparable to intermediate-risk patients, supporting an aggressive multimodal approach. Further prospective studies are warranted.