IDH wild-type glioblastoma: Predictive value of standard-of-care (SOC) MRI for establishing MGMT promoter methylation status

Abstract

Purpose Oxygen 6-methylguanine-DNA methyltransferase (MGMT) promoter methylation is associated with better chemotherapy response and prognosis in glioblastoma patients. This study evaluates the prognostic value of routine MRI findings at initial diagnosis to determine MGMT promoter methylation status. Methods A retrospective study was performed on 85 patients with histologically confirmed IDH wild-type glioblastoma. Patients were divided into two groups based on MGMT promoter status: methylated (33 [38.8%]) and unmethylated (52 [61.1%]). MRI findings were assessed using the Visually Accessible Rembrandt Imaging lexicon, and variables were analyzed using univariate analysis (X 2 /Fisher’s test) and logistic regression for independent predictors of MGMT promoter methylation. Results A thick enhancing tumoral margin (≥3 mm) was present in 67.3% of MGMT unmethylated glioblastomas and 32.7% of MGMT promoter methylated glioblastomas ( p = .05). Tumoral cortical extension was observed in 68.7% of unmethylated cases versus 31.3% in methylated cases ( p = .01). Non-enhancing tumors were predominantly MGMT methylated (83.3%). In multivariate analysis, tumoral cortical involvement and non-enhancing tumors were independent predictors of MGMT promoter methylation. In survival analysis, higher progression-free survival rates were identified in patients with MGMT promoter methylation ( p = .05) and in patients without cortical tumoral extension ( p = .05). Conclusion Our study suggests that while the predictive power of the assessed parameters is modest, thick enhancing tumoral margins and cortical tumor extension were more frequently identified in MGMT unmethylated glioblastomas. Conversely, 83.3% of non-enhancing tumors showed MGMT promoter methylation. Furthermore, MGMT promoter methylation and cortical extension were associated with progression-free survival.