MUC5AC and cholangiocarcinoma: In this case, treatment was administered with a dose of 60 Gy across eight fractions (BED, 105 Gy; EQD2 = 87.5 Gy; α/β = 10), following a standard radiation dose for intrahepatic cholangiocarcinoma; therefore, the high dose of radiation may have contributed not only to the suppression of mucin production but also to favorable local tumor control [14-17]. Gastrointestinal complications are significant adverse events associated with SBRT for the treatment of biliary tumors.