MGMT and central nervous system cancer: The association in chemotherapy response makes both genes very plausible markers for glioma prognosis in the absence of MGMT methylation as a sensitivity factor against chemotherapy, however, formal testing for a predictive effect of the methylation levels of both genes on chemotherapy response was not in the intention of the study and the analysis comparing different treatment methods in the NOA‐08 cohort lacks sufficient sample size for difference detection, and therefore, regarded as exploratory.