Overexpression of COX-2 in patients with HCC is generally higher in well-differentiated HCCs compared with less-differentiated HCCs or histologically normal liver, suggesting that COX-2 may be involved in the early stages of liver carcinogenesis [163-165] and increased expression of COX-2 in noncancerous liver tissue has been significantly associated with postoperative recurrence and shorter disease-free survival in patients with HCC [166, 167]. This evidence concerns the gene PTGS2 and hepatocellular carcinoma.