CD44 and central nervous system cancer: Specifically, higher tumor CD44 expression significantly predicted poor OS in patients with WHO stages II–III glioma (HR: 2.99, 95% CI: 1.53–5.89, P=0.002; I2=0%), but not in patients with glioblastoma (HR: 1.26, 95% CI: 0.76–2.08, P=0.47; I2=55%).