IDH1 and astrocytoma (excluding glioblastoma): However, there is uncertainty regarding the prognostic value of some of the most common genetic alterations in GBM, such as telomerase reverse transcriptase (TERT) promoter mutation, epidermal growth factor receptor (EGFR) amplification, and cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B) deletion.8,9  CDKN2A/B deletion appears prognostic for IDH-mutant astrocytoma,10,11 but its impact on the clinical outcomes of IDH-wildtype GBM has not been extensively investigated.