In serum samples, WFA-sialylated MUC1 levels (μL/mL; median, range) were significantly higher in patients with either BTC or IhCC (340, 56–2000) and patients with perihilar CC (346, 131–1910), distal CC (252, 121–804), gallbladder carcinoma (325, 56–2000), and IhCC (498, 103–2000) than in control subjects (84, 0.6–230) and those with benign biliary tract diseases (124, 25–594; Table 1). The gene discussed is MUC1; the disease is cholangiocarcinoma.