In multivariate models, the histological grade of the tumor (HR, 5.82; 95% CI, 3.53–9.58; p < 0.0001), adjuvant radiotherapy (HR, 1.87; 95% CI, 0.37–2.70; p < 0.018), IDH status (HR for IDH1 mutant status, 2.25; 95% CI, 0.99–3.86; p < 0.043), TERT status (HR for unmethylated status, 0.889; 95% CI, 0.290–1.19; p < 0.0143) were significantly associated with OS (Table 3). Here, IDH1 is linked to neoplasm.