Frequent hypermethylation of the DNA repair gene MGMT in long-term survivors of glioblastoma multiforme.

We have performed a methylation-specific PCR approach to comparatively analyze the MGMT promoter methylation status in 186 glioblastomas (GBM) from patients with classic survival and nine from patients with long-term survival (LTS GBM). The methylation rate in LTS GBM was significantly higher (77.8% vs. 39.2%, P = 0.033) which suggests that MGMT hypermethylation is a frequent hallmark of LTS GBM and contributes to characterize this intriguing GBM subtype.