SIRT1 and hepatocellular carcinoma: High SIRT1 expression was associated with poor HCC prognosis both in studies before 2015 (HR=1.69, 95%CI: 1.31-2.18, P<0.0001), and in studies published between 2015 and 2016 (HR=2.03, 95%CI: 1.45-2.84, P<0.0001).