Bile duct cancer, also known as cholangiocarcinoma, is a rare but aggressive cancer that begins in the bile ducts — the channels that carry bile from the liver to the small intestine. It can occur inside the liver (intrahepatic) or outside (extrahepatic). Often diagnosed at an advanced stage due to subtle symptoms, treatment includes surgery, chemotherapy, and targeted therapies. Early detection improves outcomes, especially in individuals with underlying liver or bile duct conditions.