In primary glioblastoma, Roder et al. [34] demonstrated in a prospective multicenter trial that achieving 0 cm3 contrast-enhancing residual tumor is associated with improved PFS and OS, and that the adverse effect of any residual (> 0 cm3) is most pronounced in MGMT-unmethylated tumors, with no significant OS difference between 0 cm3 and > 0 cm3 in MGMT-methylated tumors. This evidence concerns the gene MGMT and glioblastoma.