What Is Bile Duct Cancer?

Detailed Guide: Bile Duct Cancer

What Is Bile Duct Cancer?

The major function of the bile duct is to transport bile to the small intestine where it aids in digesting food. The bile duct is a thin tube, about 4 to 5 inches long, that reaches from the liver to the small intestine. In the liver, it begins as many small channels that gather bile from the liver cells. These all join into one tube or duct (this part of the bile duct is called the hepatic duct). About one third of the way along the length of the bile duct, the gallbladder attaches by a small duct called the cystic duct. The combined duct is called the common bile duct. The end of this part of the bile duct empties into the earliest part of the small intestine, next to where the pancreatic duct also enters the small intestine.

Cancers can develop in any part of the bile duct and, based on their location, are divided into 3 groups. About half of the cancers develop in the smaller bile duct branches inside the liver and are called intrahepatic (inside the liver) bile duct cancers. These can be confused with cancers that start in the liver cells and are called hepatic carcinomas. It is possible to tell these 2 types of tumors apart by looking at them under a microscope.

The next most common type of bile duct cancers is found in the common bile duct nearest the intestine. Doctors call these distal bile duct cancers.

The least common type is bile duct cancer that develops at the part of the hepatic duct where the bile ducts have joined and are just leaving the liver. Cancers that develop here are called perihilar cancers, or sometimes Klatskin tumors (named after the doctor who described them). Cancers beginning in these 3 different areas may cause different symptoms.

More than 95% of bile duct cancers are of the adenocarcinoma type. Adenocarcinomas are cancers of glandular cells that can develop in several organs of the body. Bile duct adenocarcinomas develop from the mucus glands that line the inside of the duct. Cholangiocarcinoma is another name for a bile duct adenocarcinoma. Today, most doctors use this term for all bile duct adenocarcinomas. In the past, doctors used this term only in describing intrahepatic or perihilar tumors, but not distal bile duct cancers.

Not all bile duct tumors are cancerous. Bile duct hamartomas and bile duct adenomas are benign (non-cancerous) tumors and, therefore, are not discussed further in this document. Hepatocellular carcinomas, which develop from liver cells, are more common than cholangiocarcinomas of bile duct cells. Hepatocellular carcinoma is discussed in more detail in the American Cancer Society document, Liver Cancer.

Adenocarcinomas that form in other organs, such as the pancreas, colon, rectum, stomach, lung, breast, or prostate, may spread through the bloodstream to the liver. These are called secondary liver cancers or liver metastases. Their prognosis and treatment are not the same as cholangiocarcinomas, and depend on where the cancer started.
Last Revised: 04/17/2006