PATH-28. MOLECULAR DIAGNOSIS FOR CENTRAL DIAGNOSIS OF BRAIN TUMORS FROM 2016 TO 2019— A REPORT FROM THE JAPAN CHILDREN’S CANCER GROUP (JCCG)

INTRODUCTION: Since 2016, the Japan Children’s Cancer Group (JCCG) has established a nationwide network that prospectively provides pathological review and molecular analysis. METHODS: Patients who were diagnosed with brain tumors between ages 0 and 29 were eligible. The central office at National Center for Child Health and Development served as a hub for the hospitals involved and institutions conducting pathological and molecular analysis, and managed the patients’ clinical information and tumor samples. Histopathology of all cases were centrally reviewed. Routine non-NGS based analyses were conducted based on histological diagnosis and included pyrosequencing for glioma-associated hot spot mutations and PFA/PFB classification for ependymoma, RT-PCR for RELA fusion and BRAF fusion, and nanostring for subgrouping medulloblastoma. In selected cases, methylation analysis, RNA sequencing and exon sequencing of 93 genes were performed in selected cases. RESULTS: In total, 985 cases were registered to this study in four years. Frozen samples were collected from approximately 80% of cases. The number increased from 152 in 2016 to 326 in 2019. They includes glioma (n=268), medulloblastoma (n=161), ependymoma (n=103), germ cell tumor (n=93), ATRT (n=29) and others. In 55 % of the glioma cases, at least one abnormality was detected by the routine analysis. The detailed analysis for atypical cases identified targetable alternations. DISCUSSION: This nationwide central diagnostic system has now been well established. Current issues and future prospective of the system will be discussed.