P20.01.B A MONO-INSTITUTIONAL RETROSPECTIVE ANALYSIS OF MENINGEAL SOLITARY FIBROUS TUMOR/ HEMANGIOPERICYTOMA: CLASSIFICATION AND GRADING SCHEMES CORRELATION WITH OUTCOME

Abstract BACKGROUND The aim of the present study was to enrol a large mono-institutional cohort of patients affected by meningeal solitary fibrous tumor (SFT)/hemangiopericytoma (HPC), collecting all available clinical features and information about treatments and outcomes, in order to: - classify this population according to the 2021 WHO CNS Classification and comparing that with the previous 2016 WHO Classification; - better characterize and analyse the prognostic significance of clinical and pathological variables; - identify patients with high risk of recurrence and metastases, to improve the management of these neoplasms, with benefits also for health service MATERIAL AND METHODS This retrospective study included 77 patients with histopathologically proven SFT/HPC. Reclassification according to the 2021 and 2016 WHO guidelines was done. Progression-free survival (PFS) and Overall Survival (OS) were evaluated for all patients. RESULTS The median follow-up period was 105 months. The median PFS and OS were 106 and 154 months, respectively. Correlating OS of patients to WHO grading we observed that all Grade 1 patients according to the 2016 WHO Classification are all still alive, while only 57% of patients with Grade 1 according to the 2021 WHO Classification are alive. At the same time, only 18% of patients with Grade 1 according to the 2016 WHO Classification relapsed, while 50% of patients with Grade 1 according to the 2021 WHO Classification relapsed. These differences resulted statistically significant (p