Bile Duct Cancer (Cholangiocarcinoma) Facts

November 22, 2024

This page was reviewed under our medical and editorial policy by Laleh Melstrom, M.D., M.S., associate professor of surgery and immuno-oncology, Division of Surgical Oncology, Department of Surgery, City of Hope^® Cancer Center Duarte

Every year, about 8,000 people in the United States are diagnosed with bile duct cancer, according to the American Cancer Society. Though it is rare overall and may occur in younger people, bile duct cancer is more common after age 70.

What Is Bile Duct Cancer or Cholangiocarcinoma?

Bile is a fluid secreted by the liver to help digest fats found in food, and bile ducts are the small tubes in and around the liver that carry this fluid to the small intestine. Cancer of the bile ducts is also known as cholangiocarcinoma. It occurs when cells in these tubes become abnormal and grow uncontrollably.

What Causes Bile Duct Cancer?

The exact cause of bile duct cancer is not known. However, researchers have linked inflammation and things that irritate the bile ducts to an increased risk for developing this cancer. These irritants may include things like stones in the bile duct or infection with a parasite. While parasites that may lead to bile duct cancer are not found in the United States, they are common in Southeast Asia.

Researchers suspect that inflammation from these causes may cause changes in the cellular DNA (mutations), which may result in cancer. These mutations may also happen randomly, with no known cause.

What Increases the Risk of Bile Duct Cancer?

A variety of risk factors may increase a person’s chances for developing bile duct cancer, but this cancer may also develop in someone with no known risk factors. It is also important to note that having one of these risk factors does not mean a person will get bile duct cancer.

Risk factors for bile duct cancers may include those listed below.

Age: Most cases of bile duct cancer are diagnosed in people who are in their 60s or 70s.

Primary sclerosing cholangitis: Also known as PSC, this is a rare condition that causes inflammation and scarring in the bile ducts. The cause is not known, but people with chronic ulcerative colitis may develop it.

Bile duct stones: Similar to but smaller than gallstones, bile duct stones may lead to inflammation in the bile ducts.

Choledochal cysts: This rare, genetic condition causes bile-filled sacs to form in bile ducts, which may lead to inflammation and cellular changes that may progress to cancer.

Liver fluke infections: People may get infected from eating raw or undercooked fish that contain these tiny parasitic worms, which may live in the bile ducts, where they may cause cancer. Though uncommon in the United States, these parasites may affect people who travel to Asia.

Hepatitis B or C infection: Long-term infections may cause cirrhosis, which leads to scarring and blockage in the bile ducts.

Inflammatory bowel disease: This includes Crohn’s disease and ulcerative colitis, which may cause chronic swelling of the gastrointestinal (GI) tract.

Changes in the connection between the bile duct and pancreas: In some cases, digestive fluids from the pancreas may flow backward, or reflux, into the bile ducts.

Polycystic liver disease: This rare, genetic condition causes cysts to grow in the liver.

Caroli syndrome: This is a rare, genetic condition in which the bile ducts are larger than usual. It may increase the risk of infection and formation of gallstones.

Ethnicity: In the United States, cancer of the bile ducts is most common among Hispanic Americans.

Obesity: Being overweight or obese may increase the risk for developing gallstones, bile duct stones, non-alcoholic fatty liver disease and hormonal changes that may lead to cancer.

Genetics: While a family history of bile duct cancer may increase risk, it remains a rare disease. Most cases are found in people with no family history of this cancer.

Alcohol: People who consume alcohol, particularly those who have liver disease due to alcohol use, are more likely to develop bile duct cancer.

Chemical exposure: People exposed to polychlorinated biphenyls (PCBs), dioxins, nitrosamines, radon or asbestos may have an increased risk of bile duct cancer.

Other possible risk factors: These may include HIV infection, smoking and chronic pancreatitis.

Types of Bile Duct Cancer

Doctors classify bile duct cancer based on where it starts to grow in the body. Bile duct cancer that begins to grow in ducts within the liver is known as intrahepatic bile duct cancer. Bile duct cancer that begins in ducts outside the liver is known as extrahepatic bile duct cancer.

Intrahepatic bile duct cancer

Intrahepatic bile duct cancer is also known as intrahepatic cholangiocarcinoma, and it accounts for a small number of bile duct cancers diagnosed. It starts in small ducts inside the liver called ductules that transfer bile from the liver to the gallbladder, which releases it during the digestive process.

Extrahepatic bile duct cancer

This cancer starts outside the liver in a pair of ducts that form the common hepatic duct. This duct joins with a duct from the gallbladder to form the common bile duct, which carries bile from the liver through the pancreas to the small intestine.

Extrahepatic bile duct cancers are classified as perihilar or distal bile duct cancers, as detailed below.

Perihilar bile duct cancer: Also known as perihilar cholangiocarcinoma or a Klatskin tumor, this type of cancer grows where the right and left bile ducts form the common hepatic duct. 

Distal bile duct cancer: Also known as extrahepatic cholangiocarcinoma, this cancer starts where the liver and gallbladder ducts form the common bile duct.