CES2 expression levels decreased significantly with the progression of cholangiocarcinogenesis, i.e. highest CES2 immunoreactive scores were seen in non-neoplastic normal biliary epithelium, while high-grade biliary intraepithelial neoplasias (BilIN grade 3) and invasive CCA showed a stepwise decrease of CES2 immunoreactivity. This evidence concerns the gene CES2 and cholangiocarcinoma.