NIMG-69. LEPTOMENINGEAL METASTASES IN IDH-WILDTYPE GLIOBLASTOMAS REVISITED: COMPREHENSIVE ANALYSIS OF INCIDENCE, RISK FACTORS, AND PROGNOSIS BASED ON POSTCONTRAST FLAIR IMAGING

Abstract

Abstract BACKGROUND To comprehensively investigate the incidence, risk factors, and prognosis of leptomeningeal metastases (LM) in isocitrate dehydrogenase (IDH)-wildtype glioblastoma patients. METHODS Total 913 IDH-wildtype glioblastoma patients with complete molecular information on IDH mutation and MGMT promoter methylation status were enrolled between 2004 and 2022. LM diagnosis was performed with MRI including postcontrast FLAIR and CSF cytology. Logistic regression analysis for LM development at initial diagnosis and recurrence was performed with clinical, surgical, imaging, and molecular data. The overall survival (OS) was compared between patients with and without LM. RESULTS The incidence of LM was 21.8% (199 patients) among patients with IDH-wildtype glioblastoma, with 11.5% (105 patients) at initial diagnosis, and 10.3% (94 patients) at recurrence. Male sex (odds ratio [OR]: 1.74, P = 0.017), MGMT promoter unmethylation (OR: 1.48, P = 0.048), nonlobar location (OR: 2.27, P < 0.001), and presence of necrosis (OR: 3.64, P < 0.001) were independent predictors of LM at initial diagnosis, whereas ventricular opening during surgery (OR: 2.96, P < 0.001) was the only independent predictor of LM at recurrence. The median OS was 16.2 months (interquartile range [IQR]: 9.6-30.4) in patients with LM and 19.3 months (IQR: 12.1-38.5) in patients without LM (log-rank test; P = 0.001). CONCLUSION The incidence of LM is high in patients with IDH-wildtype glioblastoma. Aggressive clinical, imaging, and molecular factors are correlated with LM at initial diagnosis, whereas ventricular entry warrant imaging surveillance for LM at recurrence. The prognosis of LM is not discouraging as expected, and promote reconsideration of focused clinical trials.