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Risk factors for liver cancer
A risk factor is something that increases the risk of developing cancer. It could be a behaviour, substance or condition. Most cancers are the result of many risk factors. Cirrhosis of the liver and infection with hepatitis B or C virus are the most important risk factors for liver cancer.
The chance of developing liver cancer increases with age. More men than women develop this disease. Liver cancer is more common in countries with high rates of hepatitis B and C infection.
Some people can have a higher than average risk for liver cancer. Talk to your doctor about your risk. If you are at higher than average risk, you may need to visit your doctor more often to check for liver cancer.
Risk factors are generally listed in order from most to least important. But in most cases, it is impossible to rank them with absolute certainty.
|Known risk factors||Possible risk factors|
Research shows that there is no link between drinking coffee and a higher risk for liver cancer.
Known risk factors
There is convincing evidence that the following factors increase your risk for liver cancer.
People who have cirrhosis of the liver have a higher risk for hepatocellular carcinoma, which is the most common type of liver cancer. Cirrhosis is when scar tissue replaces healthy tissue in the liver. The scar tissue blocks blood flow through the liver so it can’t function normally. Cirrhosis can be caused by:
- infection with hepatitis B or C virus
- drinking large amounts of alcohol over a long period of time
- metabolic disorders that cause liver damage
Chronic infection with hepatitis B virus (HBV), hepatitis C virus (HCV) or both viruses increases the risk of developing liver cancer. Even if cirrhosis does not develop as a result of the infection, it still increases the risk for liver cancer.
HBV can be spread from person to person through blood or other body fluids, such as semen or vaginal fluids. HCV is spread only through contact with infected blood.
Drinking 3 or more alcoholic drinks a day increases the risk of developing liver cancer. Alcohol can cause liver damage and lead to alcoholic cirrhosis.
People with HBV or HCV infection who drink alcohol every day have a greater risk of developing liver cancer than people who are infected with the virus but don’t drink alcohol.
Smoking tobacco increases the risk of developing liver cancer. The more you smoke and the longer you smoke, the greater your risk.
Aflatoxin is a type of toxin made by moulds and fungi (called a mycotoxin). It can contaminate many different foods, including corn, rice, wheat, peanuts, soybeans and sunflower seeds. It can also be found on spices, such as ginger or chilli peppers, and nuts including almonds, walnuts and pistachios.
Aflatoxin can be a problem in countries with hot, damp climates and poor storage facilities. People are most likely to be exposed to aflatoxin in Africa and Asia because there are high levels of contamination in food, stored grains, soil and water.
Aflatoxin is not a concern in Canada. The Canadian Food Inspection Agency monitors and tests nuts and nut products, as well as some dairy products, for aflatoxin contamination.
Thorium dioxide (Thorotrast) is a radioactive solution. It was used as a contrast medium in the 1950s to improve x-rays of the blood system, nasal passages and sinus cavities. After it is injected, thorium dioxide collects in the liver, spleen and bone marrow.
People who were exposed to thorium dioxide have a greater risk of developing angiosarcoma tumours, a rare type of liver cancer. The higher the dose given, the greater the risk. Cancer may develop as many as 45 years after exposure.
Hemochromatosis may also be called iron overload. It is a genetic disorder that causes the body to store higher than normal amounts of iron. The extra iron builds up in different tissues, especially the liver. When the liver stores too much iron, and the condition is not treated, the liver may be damaged.
People with untreated hemochromatosis have a higher risk of developing liver cancer.
People who have certain conditions that interfere with metabolism have a higher risk of developing liver cancer. These conditions may lead to liver failure or cirrhosis of the liver. They can also cause non-cancerous tumours called hepatic adenomas to grow. Metabolic disorders that may increase the risk of liver cancer include:
- alpha-1 antitrypsin deficiency
- porphyria cutanea tarda and acute intermittent porphyria
- hereditary tyrosinemia
- type I and III glycogen storage disease
Liver flukes are parasites that infect the liver. They are very common in Southeast Asia, in countries such Thailand, Laos, Vietnam and Cambodia. People become infected by eating raw fish that contains the eggs of the liver fluke.
Infection with Opisthorchis viverrini and Clonorchis sinensis increases the risk of cholangiocarcinoma, which is a rare type of cancer that starts in the bile ducts inside the liver.
Primary sclerosing cholangitis is a disease in which the bile ducts in the liver become inflamed, scarred and narrowed. People with this disease have a higher risk for cholangiocarcinoma.
Non-alcoholic steatohepatitis (NASH) is a more advanced form of non-alcoholic fatty liver disease (NAFLD). In NAFLD, fat cells collect in the liver of people who do not drink large amounts of alcohol. In NASH, the fatty tissue in the liver becomes inflamed and causes scar tissue to form. The main risk factor for developing NAFLD is obesity.
By itself, NAFLD does not cause any significant liver damage or increase the risk of liver cancer. But NASH may progress to liver damage and cirrhosis, which increases the risk of developing liver cancer.
Studies have shown that obesity is linked with a higher risk for liver cancer. This may be because NAFLD occurs in many people with obesity. NAFLD can progress to NASH, which increases the risk of liver cancer.
Vinyl chloride is used in the plastics industry to make polyvinyl chloride (PVC), which is used in many products. Occupational exposure to vinyl chloride increases the risk of developing both hepatocellular carcinoma and angiosarcoma tumours of the liver.
Workers who accidentally inhale radioactive plutonium have a higher risk of developing liver cancer, especially angiosarcoma.
People with diabetes appear to have a higher risk of developing liver cancer. Studies show that people with diabetes who develop liver cancer sometimes have other risk factors, such as heavy alcohol use, hepatitis infection or both. Also, many people with diabetes tend to be overweight or obese, which may also increase their risk of liver cancer.
Possible risk factors
The following factors have been linked with liver cancer, but there is not enough evidence to show they are known risk factors. More research is needed to clarify the role of these factors for liver cancer.
Schistosomiasis is an infection with a parasitic worm. People can be infected when they swim in fresh water in lakes, rivers or streams that contains the worm. Schistosomiasis is most common in Africa, parts of Southeast Asia, parts of South America (Brazil, Venezuela and the Republic of Suriname) and the Middle East. Some studies suggest that schistosomiasis may increase the risk of liver cancer, but the evidence is not yet conclusive.
Women who take birth control pills for more than 5 years may have a slightly higher risk of developing liver cancer. This risk was seen in older studies when birth control pills had different doses and formulations. More recent studies don’t note the same risk.
Some studies show that the rate of liver cancer is higher in areas where there are high levels of arsenic in the drinking water, but many of these areas also have high rates of hepatitis B infection. More study is needed to find out if arsenic exposure increases the risk for liver cancer.
Trichloroethylene (TCE) is a solvent used to remove grease from metal. It may also be used as a solvent in dry cleaning. Some studies suggest that exposure to TCE may increase the risk of developing liver cancer.
Some studies of workers exposed to polychlorinated biphenyls (PCBs) show a link between PCBs and a higher risk of liver cancer.
Betel quid (also called betel nut) is areca nut and lime wrapped in a betel leaf (called paan). Chewing betel quid is a common practice in Southeast Asia. Some studies have shown that people who chew betel quid have a higher risk of liver cancer.
Some studies show a link between dichlorodiphenyltrichloroethane (DDT) and liver cancer. DDT is a pesticide that was banned in Canada in 1972.
Unknown risk factors
It isn’t known whether or not using anabolic steroids is linked with liver cancer. It may be that researchers can’t show a definite link or that studies have had different results. More research is needed to see if anabolic steroids are a risk factor for liver cancer.
Questions to ask your healthcare team
To make the decisions that are right for you, ask your healthcare team questions about risks.
A substance used in some diagnostic procedures to help parts of the body show up better on x-rays or other imaging tests.
In most cases, contrast medium is injected into or around the structure to be examined.
Also called contrast dye or contrast agent.
The chemical processes in the body that create and use energy. It includes breaking down food and transforming it into energy, eliminating wastes and toxins, breathing, circulating blood and regulating temperature.
Metabolic means referring to or having to do with metabolism, as in metabolic rate.
The tube that carries bile (a yellow-green fluid that helps digest fat) from the liver to the duodenum (the first part of the small intestine).
Two hepatic ducts leave the liver and join to form the common hepatic duct. The cystic duct leaves the gallbladder and joins the common hepatic duct to form the common bile duct.