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Scientists have found a few risk factors that make a person more likely to develop bile duct cancer.

A risk factor is anything that affects your chance of getting a disease like cancer. Different cancers have different risk factors. Some risk factors, like smoking, can be changed. Others, like your age or family history, can’t be changed.

But having a risk factor, or even many risk factors, does not mean that a person will get the disease. And many people who get the disease have few or no known risk factors

Learn more about the risk factors for bile duct cancer and if there are things you can do that might help lower your risk.

Certain diseases of the liver or bile ducts

Certain conditions of the liver or bile ducts have been found to either cause bile duct cancer or to increase the risk of developing it.

Primary sclerosing cholangitis (PSC)

Primary sclerosing cholangitis (PSC) is a condition in which inflammation of the bile ducts (cholangitis) leads to the formation of scar tissue (sclerosis). The cause of the inflammation is not usually known. Many people with PSC also have inflammation of the large intestine, called ulcerative colitis.

Bile duct stones

Bile duct stones (hepatolithiasis) are a lot like gallstones, but much smaller. They can also cause inflammation that increases the risk of bile duct cancer.

Choledochal cyst disease

Choledochal cyst disease is a rare condition which some people are born with. It causes bile-filled sacs along the bile ducts. (Choledochal means having to do with the common bile duct.) If not treated, the bile sitting in these sacs causes inflammation of the duct walls. The cells of the duct wall may undergo pre-cancerous changes. Over time, these changes can progress to bile duct cancer.

Liver fluke infections

Liver fluke infections can happen when you eat raw or undercooked fish that is infected with these tiny parasitic worms. In humans, liver flukes live in the bile ducts and can cause bile duct cancer. There are several types of liver flukes. The ones most closely related to bile duct cancer risk are Clonorchis sinensis and Opisthorchis viverrini.

Liver fluke infection is rare in the US, but it is more common in some Southeast Asian countries. It can also affect people who travel to Asia.

Abnormal bile duct anatomy

Some people have abnormalities where the bile duct and pancreatic duct normally meet.This can allow digestive juices from the pancreas to reflux (flow back) into the bile ducts. This backward flow keeps the bile from moving through the bile ducts the way it should. People with these abnormalities are at higher risk of bile duct cancer.

Cirrhosis

Cirrhosis is damage to the liver caused by scar tissue. Cirrhosis can be caused by irritants like alcohol and diseases like hepatitis or non-alcoholic fatty liver disease. Studies have found it increases the risk of bile duct cancer.

Hepatitis B or hepatitis C

Infection with hepatitis B virus or hepatitis C virus appears to be associated with increased risk for bile duct cancers. This may be in part because long-term infections with these viruses can also lead to cirrhosis.

Inflammatory bowel disease

Inflammatory bowel disease includes ulcerative colitis and Crohn’s disease. People with these diseases have an increased risk of bile duct cancer.

Genetic Disorders

Genetic disorders are gene-related changes that you are born with. Lynch syndrome, BAP1 tumor predisposition syndrome, cystic fibrosis, and multiple biliary papillomatosis are genetic disorders associated with an increased risk of bile duct cancer. 

Older age

Older people are more likely than younger people to get bile duct cancer. Most people diagnosed with bile duct cancer are in their 60s or 70s.

Ethnicity and geography

In the US, the risk of bile duct cancer is highest among Hispanic Americans. Worldwide, bile duct cancer is much more common in Southeast Asia and China, largely because of the high rate of infection with liver flukes in these areas.

Obesity

Being overweight or obese can increase the risk of cancers of the gallbladder and bile ducts. This could be because obesity increases the risk of gallstones and bile duct stones, as well as the risk of non-alcoholic fatty liver disease. But there may be other ways that being overweight can lead to bile duct cancers, such as changes in certain hormones.

Exposure to Thorotrast

A radioactive substance called Thorotrast (thorium dioxide) was used as a contrast agent for x-rays until the 1950s, when its production and use was banned. It was found to increase the risk for bile duct cancer, as well as other types of liver cancer.

Diabetes

People with diabetes (type 1 or type 2) have been found to have a higher risk of bile duct cancer. It’s unclear whether this is because of high levels of blood sugar or because of other diabetes-associated issues such as obesity or high cholesterol.   

Alcohol

People who drink alcohol are more likely to get intrahepatic bile duct cancer. The risk is higher in those who have liver problems from drinking alcohol.

Other possible risk factors

Studies have found other factors may also increase the risk of bile duct cancer. But for these factors, the link to bile duct cancer risk is not as clear.

Other possible risk factors include:

• Smoking
• Chronic pancreatitis (long-term inflammation of the pancreas)
• Infection with HIV (the virus that causes AIDS)
• Exposure to asbestos
• Exposure to radon or other radioactive chemicals
• Exposure to dioxin, nitrosamines, or polychlorinated biphenyls (PCBs). People who work in rubber plants and automotive industries may be exposed more often to these chemicals.