The drivers of these improvements in survival across glioma subtypes are likely multifactorial including increased accuracy in molecular diagnostics, recognition of surgical advantage with early intervention, evolution in technologies for safer maximal tumor resection, more widespread use of chemoradiation, and availability of investigational agents.29–31 Across glioblastoma, IDH1/2-mutant astrocytoma, and oligodendroglioma, heterogeneity in patient populations may have contributed to the differences between non-TCGA and TCGA survival estimates. This evidence concerns the gene IDH1 and oligodendroglioma.