Overview

Bile duct cancer begins when cells in the bile duct become abnormal and grow uncontrollably, forming a mass called a tumor. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body).

About the bile duct

The bile duct 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 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 starts in the liver. Within the liver, smaller tubes (similar to small blood vessels) 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.

Types of bile duct cancer

For bile duct cancer, doctors look at both the exact location of the tumor (extrahepatic or intrahepatic) and the type of cell involved. Cancer can occur in any part of the bile duct.

Extrahepatic. The part of the bile duct that is outside of the liver is called extrahepatic. It is in this portion where cancer usually begins. A perihilar cancer, also called a Klatskin tumor, begins where many small channels join into the bile duct at the point where it leaves the liver. About two-thirds of all bile duct cancers occur here. Distal bile duct cancer 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 bile duct cancers are distal bile duct cancer.

Intrahepatic. About 5% to 10% of bile duct cancers are intrahepatic, or inside the liver.

The type of cancer depends on the type of cell where the disease began. Adenocarcinoma is the most common type of extrahepatic bile duct cancer, and accounts for about 95% of all bile duct cancers. Adenocarcinoma is cancer that begins in the mucus gland cells lining the inside of the bile duct. Cholangiocarcinoma is another term that may be used to describe this type of cancer when it begins in the bile duct.

This section is about primary bile duct cancer, which is cancer that starts in the bile duct. For information about cancer that began in another part of the body and then spread to the bile duct, please see Cancer.Net’s guide for that type of cancer.

Find out more about basic cancer terms used in this section.