IDH1 and glioma: Several pretreatment variables, such as age, performance status, extent of tumor resection, O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status, and isocitrate dehydrogenase (IDH) mutation status, are known independent prognostic and/or stratification factors in patients with glioblastoma/gliomas (9–11).