A risk factor is anything that affects your chance of getting a disease, such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancers in several organs. But risk factors are not absloute. Having a risk factor, or even several risk factors, does not mean that you will get the disease. And many people who get the disease may not have had any known risk factors.

Scientists have found several risk factors that make a person more likely to develop hepatocellular carcinoma (HCC).

Gender

Hepatocellular carcinoma is much more common in males than in females, although much of this is likely due to differences in behaviors affecting the risk factors described below. The fibrolamellar subtype of HCC occurs in about equal numbers in both sexes.

Certain Types of Chronic Viral Hepatitis

Chronic (long-term) infection with hepatitis B virus (HBV) or hepatitis C virus (HCV) is the most common liver cancer risk factor. These infections lead to cirrhosis of the liver (see below) and are responsible for making liver cancer the most common cancer in many parts of the world.

In the United States, infection with hepatitis C is the most common cause of HCC, while in Asia and developing countries, hepatitis B is more common. People infected with both viruses have a very high risk of developing chronic hepatitis, cirrhosis and liver cancer. 

HBV and HCV are spread from person to person through sharing contaminated needles (such as in drug use), unprotected sex, or childbirth. They can also be passed on through blood transfusions, although this has rarely happened in the United States since the start of blood product testing for these viruses. In developing countries, children sometimes contract hepatitis B infection from prolonged contact with family members who are infected.

Of the 2 viruses, infection with HBV is more likely to cause symptoms, such as a flu-like illness and a yellowing of the eyes and skin (jaundice). But most people recover completely from HBV infection within a few months. Only a very small percentage of adults become chronic carriers (and have a higher risk for liver cancer), but the risk is higher in infants and small children who become infected.

HCV, on the other hand, is less likely to cause symptoms. But most people with HCV develop chronic infections, which are more likely to lead to liver damage or even cancer.

Other viruses can also cause hepatitis, such as the hepatitis A virus and hepatitis E virus. But people infected with these viruses do not develop chronic hepatitis or cirrhosis, and have no increased risk of liver cancer.

Cirrhosis

Cirrhosis is a disease in which liver cells become damaged and are replaced by scar tissue. People with cirrhosis have an increased risk of liver cancer. Most (but not all) people who develop liver cancer already have some evidence of cirrhosis.

There are several possible causes of cirrhosis. Most cases in the United States occur in people who abuse alcohol. Chronic infections with HBV or HCV are also major causes of cirrhosis.

Certain types of inherited metabolic diseases (see below) can cause problems in the liver that lead to cirrhosis. Some types of autoimmune disases that affect the liver can also cause cirrhosis.

Certain inherited metabolic diseases can also lead to cirrhosis. People with hemochromatosis absorb too much iron from their food. They are more likely to develop cirrhosis because of the high levels of iron in their liver. Other rare diseases that increase the risk of liver cancer include tyrosinemia, alpha1-antitrypsin deficiency, porphyria cutanea tarda, glycogen storage diseases, and Wilson’s disease.

Diabetes

Diabetes can also increase the risk of liver cancer, usually in patients who have other risk factors such as heavy alcohol consumption and/or chronic hepatitis.

Obesity

Obesity increases the risk of developing liver cancer, probably because it can result in fatty liver disease and cirrhosis.

Aflatoxins

These cancer-causing substances are made by a fungus that contaminates peanuts, wheat, soybeans, ground nuts, corn, and rice. Storage in a moist warm environment can lead to the growth of this fungus. Although this can occur almost anywhere in the world it is more common in warmer and tropical countries. Developed countries such as the United States and those in Europe regulate the content of aflatoxins in foods through testing. Long-term exposure to these substances is a major risk factor for liver cancer. The risk is increased even further in people with hepatitis B or C infection.

Vinyl Chloride and Thorium Dioxide (Thorotrast)

These chemicals are risk factors for angiosarcoma of the liver (see the section "What Is Liver Cancer?"). They also increase the risk of developing cholangiocarcinoma and hepatocellular cancer, but to a far lesser degree. Vinyl chloride is a chemical used in making some kinds of plastics. Thorostat is a chemical that in the past was injected into some patients as part of certain x-ray tests. When the cancer-causing properties of these chemicals were recognized, steps were taken to eliminate them or mimimize exposure to them. Thorostat is no longer used and exposure of workers to vinyl chloride is strictly regulated. 

Anabolic Steroids

Anabolic steroids are male hormones that are used by some athletes to increase their strength. Long-term anabolic steroid use can slightly increase the risk of hepatocellular cancer. Cortisone-like steroids, such as hydrocortisone, prednisone, and dexamethasone, do not carry this same risk.

Arsenic

Chronic exposure to drinking water contaminated with naturally occurring arsenic, such as that obtained from some wells, increases the risk of some types of liver cancer. This is more common in parts of East Asia but may be a concern in some areas of the United States.

Birth Control Pills

Birth control pills, also known as oral contraceptives, are a cause of benign tumors called hepatic adenomas. They may also slightly increase the risk of hepatocellular cancer. Most of the studies linking oral contraceptives and liver cancer involve types of pills that are no longer used. Current birth control pills use different types of estrogens, different estrogen doses, and different combinations of estrogens with other hormones. It is not known if the newer pills significantly increase liver cancer risk.

Tobacco Use

Some studies have found a link between smoking and liver cancer, but the extent of this is not known.

Last Revised: 05/03/2007