FEN1 and hepatocellular carcinoma: The Flap endonuclease (FEN1) expression levels were also positively correlated with tumor size (P = 0.047 < 0.05), distant metastasis (P = 0.013 < 0.05) and vascular invasion (P = 0.024 < 0.05) in HCC (Li et al., 2019).