PATH-16. SURVIVAL ANALYSIS OF ADULT MIDLINE-LOCATED GLIOMAS: DOES THE H3K27 ALTERATION IN ADULT MIDLINE-LOCATED GLIOMAS ACTUALLY INDICATE A POOR PROGNOSIS?

Abstract

Abstract OBJECTIVE Although pediatric midline-located gliomas (MGs) with H3K27 alteration have been widely known to have a poor prognosis, few researchers have assessed adult MGs with H3K27 alteration. We aimed to determine the effect of H3K27 alteration on the prognosis of adult MGs. And we tried to identify the factors affecting the prognosis of diffuse midline glioma (DMG). This is the first study to investigate the prognosis of adult DMGs according to histological grade and is the largest study to investigate the survival of adult patients with DMGs. METHODS We reviewed the charts of adult patients diagnosed with MG after undergoing resection or biopsy at our institution between 2010 and 2020. The Gehan–Breslow–Wilcoxon test was used for univariate survival analysis, and the Cox regression proportional hazard model was used for multivariate survival analysis. RESULTS Among the 125 adult MGs identified, 45 (36.0%) showed H3K27 alterations. Surprisingly, the H3K27 alteration group showed significantly better median survival than the wildtype group in patients of all ages (23.1 vs. 15.9 months, p=0.040). However, after adjusting for age, the difference in survival between the H3K27-alteration and wildtype groups was not significant (p=0.121). In the survival analysis of 45 patients with DMG, low histological grade, KPS ≥ 80, total resection, and concurrent chemoradiation therapy were associated with significantly better survival. CONCLUSION Adult MGs did not show a poor prognosis due to H3K27 alterations, unlike pediatric cases. The prognosis of adult DMGs is based on the histological grade, KPS, adjuvant treatment, and extent of tumor resection.