Although nonspecific biomarkers such as carbohydrate antigen 199 (CA199) (Liang et al., 2015) and carcinoembryonic antigen (CEA) (Loosen et al., 2017) are used in diagnosis, their levels are also elevated in hepatocellular carcinoma, cholangitis, and other hepatobiliary diseases, complicating their reliability as diagnostic markers for CCA (Macias et al., 2018; Chen et al., 2002). This evidence concerns the gene CEACAM5 and cholangiocarcinoma.