IDH1 and astrocytoma (excluding glioblastoma): The overlap in clinical outcomes amongst grade 2 and 3 IDH1/2-mutant astrocytoma was readily evident, as grade 2 IDH1/2-mutant astrocytoma patients did not differ in overall survival from those with grade 3 tumors in the non-TCGA cohort (DFCI/GENIE; P = .88).