Glioma
This group comprises anaplastic astrocytomas and glioblastoma multiforme. Whereas the median overall survival of anaplastic (WHO grade III) gliomas is approximately 3 years, glioblastoma multiforme has a poor median overall survival of c. 15 months.
O-6-methylguanine-DNA methyltransferase
Methylation of the gene's promoter may play a significant role in carcinogenesis. In patients with glioblastoma, a severe type of brain tumor, the methylation state of the "MGMT" gene determined whether tumor cells would be responsive to temozolomide; if the promoter was methylated, temozolomide was more effective. On a clinical level, this translates into a prolonged survival of glioblastoma patients with a methylated "MGMT" promoter. In addition, "MGMT" methylation can be used to predict patient survival in clinical prediction models. For testing of the MGMT promoter methylation status in the clinical setting, DNA-based methods such as methylation-specific polymerase chain reaction (MS-PCR) or pyrosequencing are preferred over immunohistochemical or RNA- based assays.