MGMT and glioblastoma: Concerning the prognostic implications of the quantitative determination of the MGMT promoter methylation value, the average methylation extent of some CpG islands significantly correlated with the median OS of patients affected by GBM in three separate works.27-29 Furthermore, a recent pyrosequencing-based study showed significantly better outcomes in patients harbouring tumours with higher MGMT methylation percentages.30