What is cancer?
Liver cancer
How common is liver cancer?
Causes of liver cancer?
The human body is composed of billions of cells that are continually ageing, dying and being replaced. Cell death, replacement, growth and development are normally tightly controlled. If this control breaks down, cells begin to grow and divide abnormally, clustering together to form a lump known as a tumour. These tumours are either benign or malignant. Cancer is the name given to a malignant tumour.
Benign liver tumours
Benign liver tumours stay in the liver and do not spread to other organs or parts of the body. Usually they only grow for a limited amount of time and produce no symptoms.
Most benign tumours are found by chance. Occasionally, they may need surgical removal if they are large, liable to bleed or cause any discomfort.
Malignant tumours
Malignant cancer tumours are cells growing without control, which go on to invade, erode or destroy normal, healthy tissue.
Cancer is not a single disease. In fact, there are more than 200 different types of cancer1, each with its own name, cause and treatment.
There are two broad categories of liver cancer: secondary and primary.
1. Secondary liver cancer
Secondary liver cancer, is a cancer that first develops elsewhere in the body and then spreads (metastasises) to the liver. It is sometimes called metastatic cancer.
2. Primary liver cancer
Primary liver cancers are cancers that start in the liver. The two main types are:
- Hepatoma, also called hepatocellular carcinoma (HCC)
- Biliary tree cancer, which includes cholangiocarcinoma (bile duct cancer) and gallbladder cancer.
In the UK, around 3,400 people every year are diagnosed with primary liver cancer which represents about 1% of all cancers in the UK1. Secondary liver cancer is far more common than primary liver cancer. Most people in the UK diagnosed with tumours in their liver, will have secondary liver cancer.
Primary liver cancer is more common in men than in women. The reasons for this are not fully understood2,3. It is more likely to affect people over the age of 60 and is rare below the age of 453,4,5.
Although primary liver cancer is relatively rare in the UK, HCC is the sixth most common cancer worldwide6. It is common in sub-saharan Africa and parts of Asia such as China6,7.
Secondary liver cancer
When a cancer forms in a part of the body, a few cancer cells may break off and find their way into the bloodstream. Because your liver filters your blood, any cancer cells in the bloodstream have a high chance of settling in the liver to form a cancer nodule (metastasis).
People who are most at risk of secondary liver cancer are those with cancers of the large bowel (colon), pancreas, stomach, lung or breast8.
It is important to know where the cancer started as this will determine the type of cells which are causing the cancer and affect which treatment is best suited for you.
Secondary cancer diagnosed in the liver may be a sign of cancer in other organs. If the original (primary) cancer is too small to be detected, it is called carcinoma of unknown primary.
Primary liver cancer
1. Hepatoma (hepatocellular carcinoma, or HCC)
The main cause of HCC is cirrhosis of the liver, where the liver has become scarred as a result of damage over a long period of time. Any disease that causes cirrhosis of the liver can lead to a hepatoma, but certain causes of cirrhosis have a particularly strong link with HCC.
- Viral infections hepatitis B and C3
- Excessive alcohol consumption
- Haemochromatosis: a rare hereditary disease caused by an overload of iron in the body. High risk if not treated.
- Non-alcoholic fatty liver disease (NAFLD): specifically the advanced form non-alcoholic steatohepatitis (NASH) is thought to be the cause of many cases of cirrhosis previously labelled as of unknown cause (cryptogenic)9. It is increasingly being associated with HCC10.
Other causes of cirrhosis less frequently associated with HCC7,11,12.
- Primary biliary cirrhosis (PBC): nine out of ten people with PBC are women and have a relatively low risk of developing HCC. However, the risk is greater for men with PBC, who have a risk of developing HCC similar to those with alcohol related cirrhosis3.
- Autoimmune hepatitis: people with this condition have only a very low risk of developing HCC, even when cirrhosis is present.
Having cirrhosis does not mean you will get primary liver cancer. Around three or four people out of a hundred with cirrhosis will go on to develop HCC each year.
As well as cirrhosis, other factors can also increase your risk of developing HCC.
- Infection with two or more viruses
(coinfection) such as hepatitis B, hepatitis C or HIV leads to a greater risk than a single infection.
Both obesity and type 2 diabetes are linked with a higher risk of developing HCC, the risk being greater if both are present. This is often associated with NASH as part of a group of conditions called ‘the metabolic syndrome’11,13.
Heavy smoking, particularly in association with excessive alcohol consumption or infection with viral hepatitis is linked with HCC14.
Using anabolic steroids over a long period can lead to liver tumours. These are usually benign but can grow and rupture causing pain. These may in rare circumstances lead to HCC15.
Exposure over a long period to aflatoxin B, which may be present in mouldy rice, wheat, peanuts, corn and soybeans (particularly in areas of Asia and Africa) and the practice of chewing betel quid, also increase the risk of HCC7,11.
If more than one of these apply to you, your risk of developing HCC will be greater.
2. Biliary tree cancer
In most people, there is no clear reason why they develop cholangiocarcinoma or gallbladder cancer. However, people who have the following problems are more likely to develop cholangiocarcinoma:
- a liver problem called primary sclerosing cholangitis (PSC)4. The risk is increased by smoking5.
- chronic inflammation of the bile ducts due to multiple stones within the liver4,5
- parasitic infections (liver fluke) common in SE Asia
- cirrhosis of any cause but particularly due to viral hepatitis B and C5.
3. Fibrolamellar carcinoma
A rare variation of HCC usually found in people between 20 to 40 years old without cirrhosis being present. It is usually well contained and can be removed with surgery.