The liver is the body’s largest internal organ. It processes and stores nutrients and produces cholesterol and proteins such as albumin, clotting factors and the lipoproteins that carry cholesterol. It also secretes bile and performs many metabolic functions, including detoxification of several classes of carcinogens.
Incidence and survival rates
Liver cancer is the sixth most common cancer worldwide, with 782,000 new cases diagnosed in 2012. It is the second most common cause of death from cancer and is more common in men than women. The risk increases with age, with most cases diagnosed over the age of 75.
However, in people living in less developed countries in Asia and Africa compared with those in more developed countries worldwide, the disease can develop at a younger age (typically around the age of 40).
About 83 per cent of liver cancer cases occur in less developed countries, with the highest incidence of liver cancer in Asia and Africa and the lowest incidence in Europe and in Latin America and the Caribbean. The age-standardised rate of this cancer is more than six times higher in Eastern Asia than in Northern Europe.
The early stages of liver cancer do not usually produce symptoms, so the disease is generally advanced when it is diagnosed. Survival rates are poor: for example, in European adults diagnosed with liver cancer between 2000 and 2007, the mean age standardised survival rate at five years was approximately 12 per cent.
Lifestyle factors and liver cancer risk
In this report from our Continuous Update Project (CUP) – the world’s largest source of scientific research on cancer prevention and survivorship through diet, nutrition and physical activity – we analyse global research on how certain lifestyle factors affect the risk of developing liver cancer. This webpage forms part of the World Cancer Research Fund/American Institute for Cancer Research Third Expert Report Diet, Nutrition, Physical Activity and Cancer: a Global Perspective.
Findings on liver cancer
There is strong evidence that:
- being overweight or obese INCREASES the risk of liver cancer
- consuming alcoholic drinks INCREASES the risk of liver cancer
- consuming foods contaminated by aflatoxins (toxins produced by certain fungi) INCREASES the risk of liver cancer
- drinking coffee DECREASES the risk of liver cancer
There is some evidence that:
- consuming fish might decrease the risk of liver cancer
- being physically active might decrease the risk of liver cancer
Other causes of liver cancer
In addition to the findings on diet, nutrition and physical activity outlined above, other established causes of liver cancer include:
- other diseases
Cirrhosis of the liver increases the risk of liver cancer, and so can be seen as a cause of this cancer.
- infection and infestation
Chronic viral hepatitis is a cause of liver cancer. Infestation of liver flukes is a cause of cholangiocarcinoma.
Long term use of oral contraceptives containing high doses of oestrogen and progesterone increase the risk of this cancer.
Smoking increases the risk of liver cancer. In smokers who also have hepatitis B or hepatitis C virus infection, the risk is increased further, and those who smoke as well as consume large amounts of alcohol may also be at increased risk compared with those who do not smoke or drink.
Patients with cirrhosis (scarring of the liver due to previous damage) have the highest risk of developing hepatocellular carcinoma: approximately 90–95 per cent of people who develop hepatocellular carcinoma have underlying cirrhosis. So any cause of cirrhosis, either viral or chemical, is likely to increase cancer risk. The liver is also a common site for metastasis of tumours originating in other organs.
As for cancers at most sites, accumulated sequential changes, specifically in mature hepatocytes, lead to the development of dysplastic nodules; over the course of around five years, 30 per cent may develop into tumours . Hepatocellular carcinoma cells show numerous genetic changes, perhaps accumulated during cellular proliferation, which is part of the normal liver repair process. The hepatitis B virus related type appears to be more genetically unstable than others and acts by directly damaging cells and their DNA, whereas hepatitis C virus shows more of an indirect effect, mediated by cirrhosis.
Full references and a summary of the mechanisms underpinning all the findings can be found in the liver cancer report.
How the research was conducted
The global scientific research on diet, nutrition, physical activity and the risk of liver cancer was systematically gathered and analysed, and then independently assessed by a panel of leading international scientists in order to draw conclusions about which of these factors increase or decrease the risk of developing liver cancer.
This webpage is a summary.
For much more, download the full chapter.