Stratification by mean age showed HCC group had significantly higher leptin levels than CFC group in both “< 60” (SMD = 2.87, 95% CI (1.57, 4.17), P = 0.000) and “≥ 60” (SMD = 0.76, 95% CI (0.03, 1.49), P = 0.040). This evidence concerns the gene LEP and hepatocellular carcinoma.