IDH1 and glioblastoma: It has previously been reported that tumor location in glioblastoma is associated with several important prognostic factors including age [10], extent of resection [41], and molecular markers such as isocitrate dehydrogenase 1 (IDH1) mutation and possibly O6-methylguanine DNA methyltransferase (MGMT) promoter methylation [10, 23, 45].