LEP and hepatocellular carcinoma: HCC patients had significantly higher levels of circulating adiponectin, leptin, visfatin, and resistin compared to the controls (SMD = 1.6, 95% CI: 0.65-2.56; SMD = 2.45, 95% CI: 1.59-3.31; SMD = 2.49, 95% CI: 1.32-3.65; SMD = 4.17, 95% CI: 3.17-5.17, respectively).