The standardisation process includes four steps: (i) methylation status analysis of paired frozen and FFPE tumour samples (n = 7), and subsequent extension to 43 additional FFPE samples; (ii) validation test of methylation status in two evaluated FFPE samples at other institutions; (iii) MGMT gene expression analysis in frozen tumour (n = 7) and (iv) evaluation of the clinical behaviour of glioblastoma cases with methylated MGMT promoter. Here, MGMT is linked to glioblastoma.