The exact cause of liver cancer is unknown, but many cases are linked to a problem with the liver called cirrhosis. This is where the tissue of the liver has become scarred and cannot perform many of its usual functions.
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, but it appears that cirrhosis can increase a person's chances of developing the condition.
However, most cases of cirrhosis do not lead to liver cancer, and people without cirrhosis can also develop liver cancer.
Common causes of cirrhosis
The main causes of cirrhosis in the UK are outlined below.
Heavy and harmful drinking
The liver is a tough and resilient organ. It can endure a high level of damage that would destroy other organs and is capable of regenerating itself. But despite the liver's resilience, excessive alcohol intake 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 and it can become damaged and scarred over time.
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 can 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.
Hepatitis C is spread by blood contact. The most common ways this happens worldwide include poor medical practice with the use of contaminated needles, or injected drug use, where any item of injecting equipment (not just needles) is shared.
If you smoke or regularly drink alcohol and have hepatitis C, your risk of developing liver cancer further increases.
Early treatment of long-term hepatitis C with antiviral medication can prevent the liver becoming scarred.
Other causes of cirrhosis
Less common causes of cirrhosis in the UK are described below.
Hepatitis B is a virus that can be spread through contaminated blood and other types of bodily fluids, such as saliva, semen and vaginal fluids.
Like hepatitis C, hepatitis B is spread through blood contact. It is most commonly spread from mother to child at birth or from child to child in early life (usually in areas outside the UK where the infection is very common), and very rarely sexually or through injecting drugs.
It affects about 1 in every 200 people in the UK. Most of those infected were born in parts of the world where the hepatitis B virus is very common.
As with hepatitis C, hepatitis B can also cause inflammation and scarring of the liver over time.
If you smoke or drink and have hepatitis B, your risk of developing liver cancer further increases.
Early treatment of long-term hepatitis B with antiviral medication is not always needed, but can substantially reduce the risk of the liver becoming scarred.
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 over time, although treatment can reduce the risk of the condition leading to liver cancer.
Primary biliary cirrhosis
Primary biliary cirrhosis is a rare and poorly understood liver condition estimated to affect around 1 in every 3,000 people in England and Wales.
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 gradually become damaged. This eventually leads to a build-up of bile inside the liver, which damages the liver and causes cirrhosis.