[Genetic alterations and biomarkers for glioma]

Over the last decade, significant progress has been made in understanding glioma on a molecular level. However, optimal incorporation of molecular markers into clinical care is still controversial. Here, the potential utility of genetic alterations found in gliomas in refining histological diagnosis, prognosis, and predictive values for treatment selection is reviewed. Among all, O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation, 1p/19q codeletion, and isocitrate dehydrogenase 1 (IDH1) mutations have been identified as favorable prognostic markers. MGMT promoter methylation is the only potential predictive marker for response to temozolomide and alkylating agents in glioblastoma (GBM), but it is not of assistance in diagnostics. IDH1 mutations and 1p/19q codeletion are also useful for classifying and grading gliomas, since 1p/19q codeletion is tightly linked to oligodendroglial lineage, and IDH1 mutations are restricted to grade II/III gliomas, while not to primary GBM. BRAF fusion is a good marker for pilocytic astrocytoma. High-throughput profiling techniques for gene expression and epigenetic modification have provided new subtype classifications for GBM as well as lower grade gliomas, which may be of prognostic and predictive values. Efforts to identify molecular markers that predict the benefits of novel molecularly targeted treatments will enable better patient stratification and individualization of treatment.