MUC5AC and biliary tract neoplasm: MUC17, encoded a membrane‐bound mucin, played an antiadhesive role in cancer cells that lose their apical/basal polarization and has been reported as a potential negative prognostic biomarker for several solid tumors including breast, glioma, gastric, colon, and biliary tract cancers [36, 37, 38, 39, 40].