HIF1A and gastric cancer: Patients with T3 and T4 gastric cancer had higher HIF-1α expression in 9 studies (1188 patients; OR  = 3.050, 95% CI  = 2.067–4.501, P<0.001) than those with T1 and T2 gastric cancer, with moderate between-study heterogeneity (I2 = 53.8%, subgroup difference P = 0.027) (Table 2).