By referring to previous studies concerning the gene expression on the biliary tract epithelium exposed to the pancreatobiliary reflux as was summarized in Table 1 [8, 10–13], KRAS gene mutation and the expressions of p53 protein as well as β-catenin were assessed in the tissues from three sites as the follows: tumor cells of ICPN, background mucosa of the gallbladder surrounding the ICPN, and the epitheliums of EHBD. Here, KRAS is linked to neoplasm.