We found that the NOD2 expression level positively correlated with tumor aggressive phenotypes, including severe cirrhosis (P = 0.012), frequent vascular invasion (P = 0.007), multiple tumor number (P = 0.003), large tumor size (P = 0.032), high alpha fetoprotein (AFP, P = 0.014), advanced Edmondson grade (P = 0.002) and BCLC stage (P = 0.029) (Additional file 1: Table S3). Here, AFP is linked to Cirrhosis.