The aim of this project is to compare different techniques for analysis of MGMT in order to choose the approach with the best cost/utility ratio, which will allow the selection of patients likely to respond to TMZ chemotherapy during the first course of GBM treatment. Another aspect of this project is to evaluate the extra cost produced by TMZ treatment, and therefore the expected cost saving in the case of using a reliable predictive factor. This kind of evaluation is of great importance, as the MGMT test status is beginning to appear in the decisional care trees of high-grade gliomas The two main techniques for MGMT analysis are currently immunohistochemistry (IH) and molecular analysis of promoter methylation of the gene. Immunohistochemistry is simple and quick, but there is no consensus about labelling or evaluation of the staining, all of which could lead to variability in results. Studies of promoter methylation are currently performed by the MS-PCR technique, in particular the article published in the N Engl J Med in 2005 showing that only patients with a methylated promoter benefit from TMZ adjunction. This technique appears somewhat rudimentary compared to techniques avoiding subjectivity linked to eye reading of the gel after electrophoresis of PCR products.