HIF1A and gastric cancer: When stratifying the distant metastasis of gastric cancer, HIF-1α expression was significantly associated with distant metastasis in 5 studies (469 patients; OR  = 6.635, 95% CI  = 1.855–23.738, P = 0.004), although, with evident between-study heterogeneity (I2 = 73.3%, subgroup difference P = 0.005) (Table 2).