GBM patients with MGMT promoter methylation had significantly better OS and PFS than those with unmethylated status (OS: HR = 0.52, 95% CI 0.46–0.59, p < 0.001, I2 = 86.2%; PFS: HR = 0.51, 95% CI 0.43–0.59, p < 0.001, I2 = 70.2%; see Figure S1 in Supplementary Material), indicating the association between methylation and survival benefit in GBM patients. Here, MGMT is linked to glioblastoma.