P17.23.A GLIOMA PATHOLOGICAL DISTRIBUTIONS BASED ON THE 2021 WHO CLASSIFICATION AND 3-YEAR SURVIVAL OUTCOMES: A MULTI-CENTER COHORT FROM NATIONAL BRAIN TUMOR REGISTRY OF CHINA (NBTRC)

Abstract BACKGROUND Gliomas are the most common primary malignant brain tumors, highly associated with poor prognosis. Although relevant studies have been conducted globally, the distribution and prognostic outcomes remain insufficiently profiled in China. The National Brain Tumor Registry of China (NBTRC) comprises data from dozens of surgical centers nationwide. This study aims to characterize the distribution of glioma subtypes based on the 2021 WHO classification and estimate the 3-year survival rate in a real-world NBTRC-based multicenter cohort. METHODS Data were collected from NBTRC, which was linked to the National Mortality Registration Information Management System by the Chinese Centre for Disease Control and Prevention. We included 2,807 patients registered from Jan 1, 2020, to Dec 31, 2020, with a pathological diagnosis of glioma, across 24 hospitals in China. All patients were followed up until Dec 12, 2023. The pathological distribution of glioma patients was described and 3-year all-cause mortality was estimated using the Kaplan-Meier survival curve. RESULTS The cohort comprised a total of 2,807 glioma patients, with the following distribution: glioblastoma (NOS) accounted for 32.1%, astrocytoma (NOS) for 25.6%, circumscribed astrocytic gliomas for 9.0%, oligodendroglioma (NOS) for 8.9%, glioblastoma (IDH-wildtype) for 8.3%, astrocytoma (IDH-mutant) for 4.0%, oligodendroglioma (IDH-mutant and 1p/19q-codeleted) for 2.4%, pediatric-type diffuse high-grade gliomas for 2.1%, and other gliomas for 7.6%. According to the WHO grading system, WHO grade 4 accounted for 43.6%, grade 3 for 18.0%, grade 2 for 32.1%, and grade 1 for 6.3%. When stratified by age, circumscribed astrocytic gliomas predominated in patients aged 0-14 years, unlike older groups where glioblastoma and astrocytoma were the most common subtypes. 1,111 deaths were reported in this cohort of 2,807 patients, resulting in a 3-year all-cause mortality rate of 39.6%. When stratified by pathological subtypes, the 3-year mortality rates were: pediatric-type diffuse high-grade gliomas (75.0%), glioblastoma, NOS (69.1%), glioblastoma, IDH-wildtype (63.7%), astrocytoma, NOS (27.5%), astrocytoma, IDH-mutant (25.2%), oligodendroglioma, IDH-mutant and 1p/19q-codeleted (10.3%), oligodendroglioma, NOS (7.2%), and circumscribed astrocytic gliomas (7.1%). CONCLUSION This study presents a comprehensive analysis of glioma subtypes based on the 2021 WHO Classification, which places greater emphasis on molecular subtypes for glioma. Our findings reveal distinct prognostic differences across molecular subtypes: pediatric-type diffuse high-grade gliomas demonstrated the highest 3-year mortality rate, whereas IDH mutation and 1p/19q codeletion were associated with significantly improved survival. These findings enhance the epidemiological and prognostic understanding of gliomas.