Brain tumor
Glioblastoma multiforme (GBM) is the most aggressive (grade IV) and most common form of a malignant brain tumor. Even when aggressive multimodality therapy consisting of radiotherapy, chemotherapy, and surgical excision is used, median survival is only 12–17 months. Standard therapy for glioblastoma multiforme consists of maximal surgical resection of the tumor, followed by radiotherapy between two and four weeks after the surgical procedure to remove the cancer, then by chemotherapy, such as temozolomide. Most patients with glioblastoma take a corticosteroid, typically dexamethasone, during their illness to relieve symptoms. Experimental treatments include targeted therapy, gamma knife radiosurgery, boron neutron capture therapy and gene therapy.
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.