Although the exact cause of liver cancer is unknown, it has been linked to damage and scarring of the liver (cirrhosis).
Cancer is a condition where cells in a specific part of the body grow and reproduce uncontrollably, producing a lump of tissue known as a tumour.
In cases of liver cancer, it is uncertain why and how the cells of the liver are affected. However, it appears that damage to the liver, such as the condition cirrhosis, can increase the risk of liver cancer.
Cirrhosis is a medical term which means the tissue of the liver has become scarred and cannot perform many of its usual functions. However, it is important to point out most cases of cirrhosis do not lead to liver cancer.
In England, the main causes of cirrhosis are:
- prolonged alcohol misuse - usually over many years
- non-fatty alcoholic liver disease
- hepatitis C
These are discussed in more detail below.
The liver is a tough and resilient organ. It can endure a high level of damage that would destroy other organs. It is also capable of regenerating itself. But despite the liver's resilience, prolonged alcohol misuse over many years can damage it.
Every time you drink alcohol, your liver filters out the poisonous alcohol from your blood and some of the liver cells die. The liver can regenerate new cells, but if you drink heavily for many years, your liver will lose the ability to do this.
It is estimated that one in three cases of liver cancer are related to alcohol misuse.
Read more about alcohol misuse and alcoholic liver disease.
Non-alcoholic fatty liver disease
Non-alcoholic fatty liver disease occurs when small deposits of fat build up inside the tissue of the liver. It's a common condition and causes no noticeable symptoms in most people. However, in some people high levels of fat can make the liver inflamed. Over time, the inflammation will scar the liver.
The exact cause of non-alcoholic fatty liver disease is unclear, but it is associated with obesity and type 2 diabetes.
A long term infection of hepatitis C can cause inflammation and scarring of the liver. In England, most people infected by hepatitis C develop the infection by using contaminated needles or other drug equipment, such as mixing spoons when injecting drugs like heroin.
If you smoke and have hepatitis C, your risk of developing liver cancer further increases.
Other risk factors
Other risk factors for liver cancer include:
Hepatitis B is a virus that can be spread via contaminated blood and other types of bodily fluids, such as saliva, semen and vaginal fluids. Hepatitis B is uncommon in England and other western European countries.
A small number of people have severe symptoms similar to those of liver cancer, and can develop extensive scarring of their liver.
The risk of someone with a hepatitis B infection developing liver cancer appears to be influenced by ethnicity. People of Asian origin infected with hepatitis B have a higher-than-average chance of developing liver cancer, regardless of whether they have also developed cirrhosis of the liver.
People of other ethnic backgrounds only seem to have an increased risk of liver cancer if they also develop cirrhosis or another related liver condition, such as hepatitis C.
If you smoke and have hepatitis B, your risk of developing liver cancer further increases.
Haemochromatosis is a genetic condition where the body stores too much iron from food. The excess levels of iron have a poisonous effect on the liver and cause scarring.
People with haemochromatosis-related cirrhosis have a 1 in 10 chance of developing liver cancer. This risk decreases to 0.1 in 10 once treatment to remove the excess iron from the body begins.
Autoimmune hepatitis is a rare, genetic condition thought to affect 1 in every 7,150 people.
In autoimmune hepatitis, your immune system (the body's natural defence against infection) attacks the cells of the liver as if they are a 'foreign' infection. Exactly what triggers the attack is unknown.
If you have autoimmune hepatitis, the risk of developing liver cancer is smaller than if you have cirrhosis from one of the other common causes. This may be because most cases of autoimmune hepatitis can be treated with immunosuppressant drugs that help prevent your immune system from damaging your liver.
Primary biliary cirrhosis
Primary biliary cirrhosis is a rare and poorly understood liver condition. In England, an estimated 1 in 4,150 people is affected.
One of the main functions of the liver is to create a fluid called bile, used by the body to help break down fat. The bile is transported to the digestive system via a series of tubes called bile ducts.
For reasons that are unclear, in cases of primary biliary cirrhosis, the bile ducts are gradually damaged. This eventually leads to a build-up of bile inside the liver, which damages the liver and causes cirrhosis.
People with advanced primary biliary cirrhosis are estimated to have a 1 in 20 chance of developing liver cancer in any given year.