The percentage of Americans diagnosed with liver cancer has been rising slowly for several decades.
The American Cancer Society estimates there are about 33,000 new cases of liver cancer in the United States each year. Of these, 24,600 are found in men and 8,590 in women.
The average age at diagnosis is 63 and over 95 percent of patients with liver cancer are at least 45 years or older.
Other risk factors include:
Asian Americans and Pacific Islanders have the highest rates of liver cancer, followed by American Indians/Alaska Natives and Hispanics/Latinos, African Americans, and whites. This is because of high rates of hepatitis, particularly hepatitis B, in patients from Asia.
Most HCCs result from scarring, or cirrhosis, of the liver. The most common conditions leading to such scarring include hepatitis c and hepatitis b viruses, non-alcoholic steatohepatitis (NASH), alcohol abuse, and rarer liver diseases such as hemochromatosis and autoimmune hepatitis.
In patients with cirrhosis, liver cells are damaged and then replaced by scar tissue. The majority of people who develop liver cancer already have a history of cirrhosis.
Some types of autoimmune diseases can damage the bile ducts and lead to cirrhosis. Once cirrhosis develops, the rate of development of HCC is about 3-5% per year.
Chronic viral hepatitis
A long-term infection with hepatitis B virus (HBV) or hepatitis C virus (HCV) can lead to cirrhosis of the liver (see above) and eventually to liver cancer. Hepatitis C is the more common cause of HCC in the United States, and hepatitis B is more common in Asia and sub-Saharan Africa. Hepatitis B can sometimes cause cancer without significant cirrhosis, by directly causing “transformation” of liver cells to cancer. This has implications for treatment: it is easier to resect (cut out) a tumor if the underlying liver is healthy allowing the remainder to regenerate.
Heavy alcohol use
Alcohol abuse is a primary cause of cirrhosis leading to an increased risk of liver cancer.
One of the most significant and preventable causes of HCC is obesity. Obesity is associated with metabolic syndrome and non-alcoholic fatty liver disease, a condition in which people who consume little or no alcohol develop a fatty liver. Fatty liver disease is the way that metabolic syndrome manifests in the liver, and up to 30% of Americans have fatty liver disease today. This can progress to NASH, which in turn contributes to up to one third of HCCs. Incidence of NASH related HCC is increasing, and patients in this category may have worse outcomes from a range of cancers.
Type II Diabetes
Patients with type 2 diabetes tend to be overweight or obese, which in turn can cause liver problems.
Inherited metabolic diseases
Patients with hereditary hemochromatosis absorb too much iron from their food. They also have a higher risk of developing cirrhosis and later, liver cancer. Other rare diseases that increase the risk of liver cancer include:
- Alpha1-antitrypsin deficiency
- Porphyria cutanea tarda
- Glycogen storage diseases
- Wilson's disease
Exposure to Vinyl chloride and Thorotrast
Vinyl chloride, a chemical used in making some kinds of plastics, is now strictly regulated. Thorotrast is a chemical no longer used in certain x-ray tests.
Anabolic steroids are male hormones are used by some athletes to increase strength and muscle mass. Long-term anabolic steroid use can slightly increase the risk of hepatocellular cancer.
Drinking water contaminated with naturally occurring arsenic increases the risk of some types of liver cancer.
The parasite that causes schistosomiasis can cause liver damage and is linked to liver cancer. This parasite is not found in the US, but individuals traveling to Asia, Africa, and South America may be affected. There are other liver flukes that are commonly seen in parts of Thailand and Vietnam which can be found in uncooked freshwater fish.
Smoking has been linked to many forms of cancer, and is a major risk factor for liver cancer.