SURG-40. PEDIATRIC LOWER GRADE GLIOMA SURGERY IN THE ERA OF GENOMIC MEDICINE

Abstract INTRODUCTION In the 2021 WHO Brain Tumor Classification, pediatric-type gliomas are distinctly categorized from their adult counterparts. The continual evolution of cancer genomics has significantly broadened the spectrum of available treatment options. Here we would like to consider surgery for pediatric low-grade gliomas. METHODS We retrospectively analyzed 41 cases of low-grade gliomas or glioneuronal tumors in pediatric patients who underwent surgery at our institute from 2002 to 2023. We discussed surgical strategies based on molecular classification. RESULTS Among the cases, there were 34 gliomas and 7 glioneuronal tumors. According to the new WHO classification, they corresponded to 1) Adult-type diffuse gliomas, 2) Pediatric-type diffuse low-grade gliomas, 3) Circumscribed astrocytic tumors, or 4) Glioneuronal and neuronal tumors. Cases without molecular diagnosis were also considered in light of the new WHO classification. Among molecularly diagnosed astrocytomas involving the cerebral hemisphere, brain stem, spinal cord, there were no cases of 1), and 2) 3) were the main cases. It is important in surgical selection to note that these cases generally have a more favorable prognosis compared to the adult type and have usefulness in diagnosing MAPK pathway abnormalities leading to the selection of molecularly targeted drugs. 3) includes pilocytic astrocytoma, subependymal giant cell astrocytoma, and pleomorphic xanthoastrocytoma. Among these, in the treatment of pilocytic astrocytoma of the visual tract and hypothalamus, biopsy is essential for molecular diagnosis and therapeutic agent selection. 4) is mainly an epilepsy-related tumor. While their removal contributes to genetic diagnosis and epileptic seizure control, total removal may not always be deemed necessary. CONCLUSION Based on the new WHO classification, a reevaluation of treatment strategies for pediatric brain tumors is necessary.