RBIO-06. CLINICAL AND MOLECULAR PREDICTORS OF RADIATION RESPONSIVENESS IN MENINGIOMAS: A MULTICENTER RETROSPECTIVE COHORT STUDY

Abstract BACKGROUND Aside from surgery, radiotherapy (RT) remains the only standard of care treatment for meningiomas. However, few studies have identified clinical/molecular biomarkers associated with responsiveness to RT and optimal timing after surgery controversial. We aimed assess outcomes in a large multi-institutional cohort RT-treated meningiomas identify clinical factors DNA methylation RNA expression markers progression-free survival (PFS) post-RT. METHODS Patients intracranial who underwent fractionated between 1997-2018 were included. DNA-methylation using Illumina 850K EPICArray RNA-sequencing performed on tumours sufficient tissue. Primary endpoints radiographic recurrence progression time completion. RESULTS 404 included analysis. Of these, 167 (41.3%) recurred post-RT, usually within 5-years RT. Previous meningioma, having WHO grade 3 older age at diagnosis independently poorer PFS Following propensity score matching, patients that received adjuvant had significantly better post-RT compared those salvage (p=0.04). 220 these segregated into two distinct groups (RT-resistant RT-sensitive) based unsupervised consensus clustering. able predict than all factors. Differential RNA-expression analysis showed up-regulation pathways involved chromosome segregation mitotic cell cycle down-regulation fatty acid metabolism RT-resistant CONCLUSION While there are paucity can reliably meningioma’s response RT, may aid differentiating RT-sensitive tumours. receive prolonged has already occurred.