Bile duct cancer causes and risk factors

Bile ducts play a significant role in the proper functioning of the digestive system. Bile duct system problems, such as inflammation, irritation or an obstruction, may cause digestive issues or jaundice. They may also develop into a chronic (long-lasting) disease. Some of these conditions are considered risk factors for bile duct cancer.

What is cholangiocarcinoma or bile duct cancer?

Bile duct cancer, or cholangiocarcinoma, occurs when cells in the bile duct become damaged or mutated. These damaged cells begin to grow and divide out of control and form a tumor or tumors.

Bile duct cancer (cholangiocarcinoma) is uncommon, accounting for 10 percent to 20 percent of liver cancers. The exact cause of bile duct cancer is not known, but research indicates that inflammation may play a role in altering the cells' DNA, causing cancer to form and grow.

Is bile duct cancer hereditary?

Bile duct cancer is not believed to be caused by genetics inherited by family members. Several risk factors, however, may increase the risk for developing bile duct cancer.

Bile duct cancer (cholangiocarcinoma) risk factors

Bile duct cancer risk factors are listed below.

Age: The average age of patients with bile duct cancer found inside the liver is 70. When bile duct cancer develops outside the liver, the average age at diagnosis is 72.

Chronic irritation or inflammation of the bile duct: Some conditions that cause chronic inflammation may increase the risk for developing bile duct cancer. For instance, bile duct stones may form in the bile duct itself. But in some cases, gallstones from the gallbladder become lodged in the bile duct, and these may irritate the bile duct. Irritation may also stem from ulcerative colitis (inflammation of the gastrointestinal tract) and primary sclerosing cholangitis (PSC), an autoimmune disease that causes inflammation of the bile duct and scarring.

Diabetes: Patients with type 1 and type 2 diabetes have a higher-than-normal risk for developing bile duct cancer. However, it’s still considered low risk.

Ethnicity: Certain ethnic groups have an increased risk of bile duct cancer. In the United States, it’s highest among Hispanic-Americans. People in China and Southeast Asia also face increased risk due to high infection rates from liver flukes, a type of parasite.

Excessive alcohol use and/or cirrhosis of the liver: Alcohol abuse is a common cause of cirrhosis of the liver.

Exposure to hazardous chemicals: Exposure to certain chemicals have been linked to an increased risk of bile duct cancer. These include dioxins, nitrosamines, polychlorinated biphenyls (PCBs), asbestos, radon and thorotrast (thorium dioxide, a radioactive substance previously used as a contrast agent for certain X-rays).

Family history: Although a family history of bile duct cancer may increase a person’s bile duct cancer risks, the risk is low because this is a rare disease. Most cases of bile duct cancer do not appear to be hereditary.

Hepatitis infection: Long-term infection with hepatitis B or C virus may increase risk. This is possibly because both viruses may cause cirrhosis of the liver, which increases a person's liver cancer risk.

Liver or bile duct diseases: Some diseases of the liver or bile duct, such as polycystic liver disease, pancreatitis (inflammation of the pancreas), irritable bowel syndrome, choledochal cysts (bile-filled sacs outside the liver with pre-cancerous cells) and Caroli’s syndrome (an inherited condition present at birth that causes dilation or widening of the intrahepatic bile ducts), may increase a person’s bile duct cancer risks.

Non-alcoholic fatty liver disease (NAFLD): This is a type of disease in which extra fat builds up in the liver cells. It’s not caused by alcohol use. Over time, it may lead to liver swelling and scarring that may potentially become cancerous.

Obesity: Being obese may increase the risk for developing some cancers, including bile duct and liver cancer.

Parasitic infections: A water-borne parasite called liver fluke (Clonorchis sinensis and Opisthorchis viverrini), which is commonly found in some parts of Asia and Europe, may infect the bile duct and cause cancer.

Smoking: Tobacco use may increase the risk for developing bile duct cancer.

How to lower the risk of bile duct cancer

While it’s not always possible to prevent bile duct cancer, a number of steps patients may take have been found to help lower the risk. Among them:

• Maintain a healthy weight and stay physically active.
• Avoid risky behaviors, such as needle sharing, that may increase the risk of contracting hepatitis C.
• Prevent hepatitis B by getting vaccinated against it.
• Limit or avoid alcohol consumption.
• Quit smoking.
• Avoid exposure to chemicals such as asbestos, radon and dioxin.

Next topic: What are the symptoms of bile duct cancer?