IDH2 and neoplasm: Factors identified as significantly associated with OS at univariate analysis (p < 0.05) were (Table 3): age, KPS, the pre-operative tumor volume, the infiltrative growth index ΔVT2T1, both EOR and the post-operative tumor volume, the expression of Ki67, the presence of mutated IDH1 or IDH2 genes, the 1p/19q co-deletion, the tumor molecular class, and the methylation status of the MGMT promoter.