In multivariate analyses, the correlation between CDKN2A homozygous deletion and worse outcomes was significant and persisted even after adjusting the population for tumor recurrence and age over 36.5 years, which are recognized as poor prognostic factors (p < 0.001, hazards ratio [HR]: 2.536, 95% confidence interval [CI]: 1.195-5.271 for grade 3 OG and p = 0.02, HR: 1.723, 95% CI: 1.012-2.936 for IDH-wt GBM). The gene discussed is IDH1; the disease is glioblastoma.