Of the seven studies, a statistically significance between HIF-1α expression and vascular invasion was observed in four studies [9], [10], [13], [14].The pooled estimate of correlation between HIF-1α expression and vascular invasion was significant [OR = 2.21 (95% CI: 1.06, 4.57)] (Fig. 4), the heterogeneity was evident (χ2 = 26.34,Ι2 = 77.2%,P<0.001).Subgroup analysis showed a trend that elevated HIF-1α levels were associated with vascular invasion in HCC patients with preoperative adjuvant antitumor therapy [OR = 2.32 (95% CI:1.14, 4.74)]. Here, HIF1A is linked to hepatocellular carcinoma.