Accordingly, the ideal CEA cut-off value that we established for our cohort for the differentiation between CCA patients and healthy controls (1.55 μg/l) was distinctly lower than the standard cut-off value and even when comparing CCA patients with our smaller cohort of PSC patients this respective cut-off value was only slightly higher (1.85 μg/l), suggesting a low variation of CEA levels in a setting of chronic cholangitis. Here, CEACAM5 is linked to chronic cholangitis.