MGMT and glioblastoma: While we observed that the MGMT status is positively and significantly correlated to the clinical outcome in the PR group (OS of 31.8 months for patients with MGMT methylated GBM with respect to only 13 months for MGMT unmethylated GBM, PFS of 13 vs. 7 months, respectively), in the group of patients who underwent a GTR we did not observe any significant association between OS or PFS and the methylation status of MGMT gene.