Liver cancer develops when some cells begin to grow abnormally. While it's not clear
why this occurs, it is believed that cancer occurs when there has been damage to
the DNA, which is the substance that stores the instructions for every chemical
process in your body, including the rate of cellular growth. When damage occurs
to your DNA, cells may grow out of control and eventually form a tumor.
The following factors may damage the DNA in liver cells:
Cirrhosis
Excessive use of alcohol is the most common cause of cirrhosis in the United States.
Cirrhosis results in irreversible scarring in the liver. Hereditary hemochromatosis,
which causes excess iron to collect in your liver and other tissues, can also lead
to cirrhosis.
Hepatitis B and C
The most common cause of liver cancer worldwide, is chronic infection with the hepatitis
B virus (HBV) or hepatitis C (HCV). In the United States, hepatits C infection is
responsible for half the new cases of hepatocellular carcinoma, the most frequent
cause of primary liver cancer. Most cases of hepatitis C is spread through blood
transfusions that hasn't been screened for the virus, through needles used in
tattooing or body piercing or through sexual transmission. HBV is transmitted primarily
through unprotected sex and contaminated needles. Women infected with HBV can pass
the virus on to their unborn children.
Primary billiary cirrhosis
This condition involves an inflammation of the bile ducts in the liver and produces
a sharp increase in an individual's risk for cholangiocarcinoma, a type of primary
liver cancer. People with this condition should undergo routine cancer screening
tests.
Long-term exposure to aflatoxins
Although the risk of exposure to aflatoxins in the United States is small, the toxins
have been found in corn and corn products, peanuts and peanut products, cottonseed,
milk, Brazil nuts, pecans, pistachios and walnuts. These are highly toxic carcinogens
that can develop when certain crops or foods are contaminated with the fungus Aspergillus
flavus. Aflatoxins can damage the P53 gene, which functions to prevent excessive
cell growth. The Food and Drug Administration has implemented several procedures
to monitor and identify aflatoxins in the food supply.
Vinyl chloride and thorium dioxide (Thorotrast)
Vinyl chloride is a chemical used to manufacture plastics. At one time, Thorotrast
was given to people undergoing X-ray tests. Both chemicals have been associated
with the development of rare cancers that start in the liver's blood vessels.
Arsenic
Arsenic, a known carcinogen, can lead to the development of liver cancer. Arsenic
is odorless and tasteless and can enter drinking water supplies from natural deposits
in the earth or from agricultural and industrial practices. The EPA has set the
arsenic standard for drinking water at .010 parts per million (10 parts per billion)
to protect consumers served by public water systems from the effects of long-term,
chronic exposure to arsenic.
Ulcerative colitis
This is an inflammatory condition of the colon and digestive tract which can cause
changes within the bile ducts and raises your risk of cholangiocarcinoma, a type
of primary liver cancer.
