In a series of cholangiocarcinoma patients without PSC, the sensitivity of CA 19‐9 concentrations >100 U/mL in diagnosing cholangiocarcinoma was 53%.29 However, although CEA is also measured frequently, it has been reported to have unsatisfactory sensitivity and specificity for cholangiocarcinoma.30, 31 In the current study, elevated values of CEA were noted in 54.5% of mucinous cholangiocarcinoma patients. The gene discussed is CEACAM5; the disease is pancreatic serous cystadenoma.