Cholangiocarcinoma (or bile duct cancer) arises from the tissues in the bile duct, which is a 4-inch to 5-inch tube that connects the liver and gallbladder to the small intestine.
The bile duct allows bile, which is made in the liver and stored in the gallbladder, to flow into the small intestine. Bile is a liquid that helps to both break down fats found in foods and helps the body get rid of waste material filtered out of the bloodstream by the liver.
The bile duct originates in the liver. Within the liver, smaller tubes, similar to capillaries, drain bile from the cells in the liver into larger and larger branches, ending in a tube called the common bile duct. Outside of the liver, the bile duct drains into the small intestine. The gallbladder is a reservoir that holds bile until food reaches the intestines. It is attached by a small duct, called the cystic duct, to the common bile duct about one-third of the way down the bile duct from the liver. The end of the bile duct empties into the small intestine.
Cancer can occur in any part of the bile ducts. The part of the tube that is outside of the liver is called extrahepatic. It is in this portion of the bile duct where cancer usually arises. A perihilar cancer begins where many small channels join into the bile duct at the point where it leaves the liver. About two-thirds of all cholangiocarcinomas occur here. Distal cholangiocarcinoma occurs at the opposite end of the duct from perihilar cancer, near where the bile duct empties into the small intestine. About one-fourth of all cholangiocarcinomas are distal cholangiocarcinomas. About 5% to 10% of cholangiocarcinomas are intrahepatic, or inside the liver.
Liver Diagram
Adenocarcinoma is the most common type of extrahepatic cholangiocarcinoma, and accounts for up to 95% of all cholangiocarcinomas. Adenocarcinoma is cancer arising from the mucus glands lining the inside of the bile duct.
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