Overexpression of IER5 was linked to worse OS in WT IDH status patients [HR = 2.405 (1.481–3.905), P < 0.001], patients without 1p/19q codeletion [HR = 4.320 (3.208–5.816), P < 0.001], patients who had a primary therapy outcome of PD [HR = 3.290 (1.979–5.471), P < 0.001], patients with astrocytoma [HR = 5.173 (2.905–9.211), P < 0.001], patients with glioblastoma [HR = 1.919 (1.174–3.138), P = 0.009], and WT PIK3CA status patients [HR = 3.738 (2.799–4.993), P < 0.001]. The gene discussed is PIK3CA; the disease is glioblastoma.