Overview

Bile duct cancer begins when cells in the bile duct become abnormal and grow uncontrollably. These cells form a growth of tissue, called a tumor. 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.

Cancer can occur in any part of the bile duct. 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. About 5% to 10% of bile duct cancers are intrahepatic, or inside the liver.

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 glands lining the inside of the bile duct. Cholangiocarcinoma is another term that may be used to describe this type of cancer.

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 spread to the bile duct, please see Cancer.Net’s guide for that type of cancer.

Statistics

Primary bile duct cancer is a rare disease. Each year, an estimated 2,000 people in the United States are diagnosed with bile duct cancer. The number of new cases of bile duct cancer is increasing, mostly due to rising rates of intrahepatic bile duct cancer. The reason for this increase is not known. It may be due to the use of more accurate tests to diagnose this type of cancer. Previously, intrahepatic bile duct cancer may have been thought to be a different type of cancer. In some parts of the world, a parasite called a liver fluke can infect the bile duct and cause cancer. Liver flukes are very common in Asia and the Middle East, and therefore bile duct cancer is more common in these regions. Also, gallstones and inflammatory conditions of the gastrointestinal (GI) tract, such as ulcerative colitis or an associated condition called sclerosing cholangitis (PSC), an autoimmune disease in which the body’s immune system attacks the bile ducts and causes scarring, increase the risk of bile duct cancer.

The five-year relative survival rate (the percentage of people who survive at least five years after the cancer is detected, excluding those who die from other diseases) for people diagnosed with early-stage bile duct cancer depends on the location of the tumor and if or where it has spread.

Cancer survival statistics should be interpreted with caution. These estimates are based on data from thousands of cases of this type of cancer in the United States and may not apply to a single person. It is not possible to tell a person how long he or she will live with bile duct cancer. Because the survival statistics are measured in five-year intervals, they may not represent advances made in the treatment or diagnosis of this cancer.

Source: American Cancer Society and Mayo Clinic

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