Risks and causes of bile duct cancer
In most cases we don't know what causes bile duct cancer, but there are some things that can increase the risk. These include being older or having medical conditions that cause long term (chronic) inflammation of the bile ducts. But your overall risk is still low.
Other risk factors depend on the type of bile duct cancer and where in the world you live.
What is a risk factor?
Anything that can increase your risk of getting a disease is called a risk factor.
Different cancers have different risk factors. Having one or more of these risk factors doesn't mean you will definitely get that cancer.
Getting older
The risk of getting bile duct cancer increases as people get older. It can develop at any age but most people are aged 65 and over. But it’s important to remember that bile duct cancer is rare, so the risk of developing it is still small.
Primary sclerosing cholangitis
Primary sclerosing cholangitis (PSC) is a rare type of inflammation of the bile ducts. Doctors don't know what causes it.
People with PSC may have an increased risk of developing cancer of the bile ducts. One study based in the Netherlands found that more than 5 in 100 people with PSC (more than 5%) went on to develop bile duct cancer.
Liver flukes
Liver flukes are worms that get into the bile ducts. Having them increases the risk of bile duct cancer. People get liver flukes from eating food that contains them, such as raw fish.
They are not usually a cause of bile duct cancer in the UK. But liver flukes are a major problem in Asia where bile duct cancer is much more common.
Choledochal cysts
A choledochal cyst (pronounced kol-eh-doke-al sist) is where part of the bile duct swells and gets wider (dilates). They are very rare.
People with choledochal cysts have them from birth. They usually develop symptoms in early childhood. But some people do not develop any symptoms until they are an adult. Doctors usually remove choledochal cysts to reduce the risk of developing bile duct cancer.
Caroli disease is a type of choledochal cyst. It is a very rare condition you are born with. It makes the bile ducts in the liver dilate. This can increase the risk of developing cancer in the bile ducts in the liver (intrahepatic bile duct cancer).
Doctors don’t know exactly what causes choledochal cysts. Or why they increase the risk of bile duct cancer.
Bile duct stones and gallstones
Bile duct stones are made of tiny amounts of fats and 
. They stick together to form a stone. They can start in the bile ducts. Or they can start in the gallbladder and move to the bile ducts. Stones that start in the gallbladder are called gallstones.
Stones that start in the bile ducts usually develop after an infection. Or because of the slow movement of bile through the ducts.
Gallstones can be caused by changes in body weight and some medicines.
Liver cirrhosis
Cirrhosis is scarring of the liver caused by earlier damage. The scarring can cause problems with the way the liver works. Things that cause cirrhosis include:
- long term infection with a virus such as hepatitis B or C
- long term alcohol drinking
- a condition called
non-alcoholic fatty liver disease
Liver cirrhosis can increase the risk of bile duct cancer. Especially intrahepatic bile duct cancer.
Inflammatory bowel disease (IBD)
Ulcerative colitis is a type of IBD. It causes inflammation of the bowel. Some IBDs like ulcerative colitis, can increase the risk of bile duct cancer.
Most people affected by PCS also have ulcerative colitis.
Exposure to plutonium
Plutonium is an element left over from making energy in nuclear reactors. It is .
Very few people in the UK work with plutonium. If you do, there are regulations in place to protect you.
Thorotrast
Thorotrast (thorium dioxide) was a dye (contrast medium) that was used until the 1960’s. It made x-ray pictures clearer.
People who have had Thorotrast in the past have a higher chance of developing bile duct cancer.
Where there isn’t clear evidence
Some factors might increase the risk of bile duct cancer but there isn’t enough evidence to be sure. These include:
-
medical conditions including hepatitis B or C infection and diabetes
-
drinking alcohol
-
smoking tobacco
-
having high blood pressure
-
being overweight or obese
-
taking steroids to increase the amount of muscle in the body
-
chewing betel quid - a combination of betel leaf, areca nut and slaked lime
Other possible causes
There are often stories about potential causes of cancer in the media. It isn’t always clear which ideas are supported by evidence. There might be things you have heard of that we haven’t included here. This is because either there is no evidence about them or it is less clear.
