The human body is composed of billions of cells that are continually growing old, 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 that 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 cancer, each with its own name, cause and treatment.
Liver cancer
There are two broad categories of liver cancer: secondary and primary.
1. Secondary liver cancer
Secondary liver cancer, sometimes called metastatic, is a cancer that first develops elsewhere in the body and then spreads to the liver.
Secondary cancer diagnosed in the liver may be an early sign of cancer in other organs.
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.
How common is liver cancer
In the UK, secondary liver cancer is far more common than primary liver cancer. Although there are no exact figures, about 15,000 people every year will develop secondary liver cancer. In comparison, about 2,600 people every year are diagnosed with primary liver cancer.
Although rare in the UK and other developed countries, primary liver cancer is relatively common in Africa and Asia.
What are the causes of liver cancer?
Secondary liver cancer
A primary cancer, forming somewhere else in the body, is always the cause of secondary liver cancer.
When a cancer forms in another part of the body, a few cancer cells may break off and find their way into the bloodstream. Because the liver filters the blood, any cancer cells in the bloodstream have a high chance of settling in the liver to form a cancer nodule (called metastases).
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 primary liver cancer 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. These include the viral infections hepatitis B and C, the cirrhosis due to excessive alcohol, or haemochromatosis (a rare hereditary disease caused by an overload of iron in the body).
Having cirrhosis does not mean you will get primary liver cancer. Only three or four people out of a hundred with cirrhosis will go on to develop HCC.
2. Biliary tree cancer
In most people, there is no clear reason why they develop cholangiocarcinoma or gall bladder cancer. However, people who have the following problems are more likely to develop cholangiocarcinoma:
- a liver problem called primary sclerosing cholangitis (PSC)
- chronic inflammation of the bile ducts due to multiple stones within the liver or parasite infections (liver fluke).