MGMT and neoplasm: After adjusting for age, extent of resection, Karnofsky performance status, and presence of residual tumor and O6-methylguanine DNA methyltransferase (MGMT) promoter methylation status, no significant difference in OS (HR = 1.6, 95% CI: 0.8-3.3; P = .22) and PFS (HR = 0.8, 95% CI: 0.4-1.6; P = .56) was detected between two groups (18).