As several studies suggested that CA19-9 and CEA are also elevated in the serum of patients with benign cholangiopathies and might therefore be unsuitable for early detection of CCA in this setting15,31, we next compared serum levels of CA19-9 and CEA in patients with CCA and patients with primary sclerosing cholangitis (PSC, n = 24) and no evidence of malignant transformation. Here, CEACAM5 is linked to pancreatic serous cystadenoma.