MGMT and glioblastoma: In subgroup analysis, OS was significantly longer in the high postoperative PNI group than in the low postoperative PNI group in patients who were male (P <  0.001) and young (age < 60 years, P = 0.003), had MGMT promoter methylation (P = 0.004), received gross total resection of GBM (P = 0.001), had a postoperative KPS score ≥ 70 (P = 0.005), and received postoperative chemoradiotherapy, P = 0.001, Fig. 2A-F).