Five studies [14, 15, 17, 20, 21] investigated the association between GLUT-1 expression and tumor size (odds ratio [OR]=2.16, 95% CI=1.2-3.9, p=0.01; Table 3) and lymph node metastasis (OR=3.29, 95% CI=1.38-7.84, p=0.007; Table 3). This evidence concerns the gene SLC2A1 and neoplasm.