Causes of cancer of the bile duct

/Home/Types of Cancer/Bile Duct Cancer

Causes of cancer of the bile duct
Last reviewed: 19/12/2008
NHS

How cancer begins

Cancer begins with an alteration to the structure of deoxyribonucleic acid (DNA) that is found in all human cells.

This alteration is known as a genetic mutation. The DNA provides the cells with a basic set of instructions, such as when to grow and reproduce.

However, the mutation in the DNA changes these instructions so that the cells carry on growing. This causes the cells to reproduce in an uncontrollable manner, producing a lump of tissue that is known as a tumour.

How cancer spreads

Left untreated, cancer can quickly grow and spread to other parts of your body.

Cancer usually spreads via the lymphatic system, which is a series of glands (or nodes) that are distributed throughout your body, much like your blood circulation system.

These glands produce many of the specialised cells that are needed by your immune system.

Once the cancer reaches the lymphatic system, it is capable of spreading to any other part of your body, including your bones, blood and organs.

Risk factors for bile duct cancer

It is not known what triggers the development of bile duct cancer but some definite risk factors have been identified. These risk factors are outlined below.

Primary sclerosing cholangitis (PSC)

Primary sclerosing cholangitis (PSC) is a rare type of liver disease that causes chronic (long-lasting) inflammation of the liver. The exact cause of PSC is unknown, and the condition mainly affects people who are between 30-50 years of age.

It is estimated that between 9-14% of people with PSC will go on to develop bile duct cancer, usually within two years of being diagnosed with PSC. Your risk of developing bile duct cancer is thought to be increased if you have PSC and you smoke tobacco.

See the Useful links section, above, for more information about PSC.

Viral hepatitis

Hepatitis B and hepatitis C are two types of viral liver infection that are thought to cause a ten-fold increase in the risk of a person developing bile duct cancer.

This risk is increased further if a person with hepatitis C damages their liver by drinking excess amounts of alcohol (cirrhosis). In such circumstances, the risk of developing bile duct cancer is thought to be a 1,000 times higher compared to that of the general population.

Parasitic infection

Liver flukes are a type of parasitic insect that are known to increase the risk of developing bile duct cancer. You can become infected with liver flukes by eating undercooked fish that has been contaminated with fluke eggs.

However, liver fluke infections are usually only a problem in Asia (particularly Thailand) and Africa where liver flukes are more widespread.

Billiary stones

Billiary stones are similar to gallstones except they form inside the liver rather than inside the gallbladder.

Billiary stones are rare in western Europe, but are relatively common in parts of Asia, such as Japan and Taiwan. It is estimated that approximately 10% of people with billiary stones will go on to develop bile duct cancer.

Exposure to toxins

Exposure to certain chemical toxins is known to increase the risk of developing bile duct cancer.

Thorotrast, for example, is a chemical that will increase your likelihood of developing bile duct cancer if you are exposed to it. It was widely used in radiography until it was banned during the 1960s after its dangerous properties were fully understood.

Other toxins that may increase your chances of developing cancer of the bile duct include:

Asbestos: a fire-resistant fibre that was widely used in construction and manufacturing but has now been banned in this country.
Polychlorinated biphenyls (PCBs): a chemical that is used in manufacturing and building but, like asbestos, has now been banned.