Liver Cancer Health Article

Definition

Liver cancer is a form of cancer with a high mortality rate. Liver cancers are classified into two types. They are either primary, when the cancer starts in the liver itself; or metastatic, when the cancer has metastasized (spread) to the liver from some other part of the body.

Primary liver cancer

Primary liver cancer is a relatively rare disease in the United States, representing about 2% of all malignancies. It is much more common in other parts of the world, representing from 10-50% of malignancies in Africa and parts of Asia. According to the American Cancer Society, in the United States during 1998, more than 14,000 new cases of primary liver cancer were diagnosed, and approximately 13,000 deaths were attributable to it.

TYPES OF PRIMARY LIVER CANCER. In adults, most primary liver cancers belong to one of two types: hepatomas, also known as hepatocellular carcinomas, which start in the liver tissue itself; and cholangiocarcinomas, which are cancers that develop in the bile ducts

inside the liver. About 90% of primary liver cancers are hepatomas. In the United States, about one person in every 40,000 will develop a hepatoma; in Africa and Asia, over 8 persons in 40,000 will develop this form of cancer. Two rare types of primary liver cancer are mixed-cell tumors and Kupffer cell sarcomas.

There is one type of primary liver cancer that usually occurs in children younger than four years of age and between the ages of 12-15. This type of childhood liver cancer is called a hepatoblastoma. Unlike liver cancers in adults, hepatoblastomas have a good chance of being treated successfully. Approximately 70% of children with hepatoblastomas experience complete cures. When the tumor is detected early, the survival rate is over 90%.

Metastatic liver cancer

The second major category of liver cancer, metastatic liver cancer, is about 20 times as common in the United States as primary liver cancer. Because blood from all parts of the body must pass through the liver for filtration, cancer cells from other organs and tissues easily reach the liver, where they can lodge and grow into secondary tumors. Primary cancers in the colon, stomach, pancreas, rectum, esophagus, breast, lung, or skin are the most likely to metastasize to the liver. It is not unusual for the metastatic cancer in the liver to be the first noticeable sign of a cancer that started in another organ. Second only to cirrhosis, metastatic liver cancer is the most common cause of fatal liver disease.

Risk factors for primary liver cancer

The exact cause of primary liver cancer is still unknown. In adults, however, certain factors are known to place some individuals at higher risk of developing liver cancer. These factors include:

• Gender. The male/female ratio for hepatoma is 4:1.
• Age over 60 years.
• Environmental exposure to carcinogens (cancer causing substances). Examples of environmental carcinogens are aflatoxin, substance produced by a mold that grows on rice and peanuts; thorium dioxide, used at one time as a contrast dye for x rays of the liver; and vinyl chloride, used in manufacturing plastics.
• Use of oral estrogens for contraception (birth control).
• Hereditary hemochromatosis. Hemochromatosis is a disorder characterized by abnormally high levels of iron storage in the body. It often progresses to cirrhosis.
• Cirrhosis. Hepatomas appear to be a frequent complication of cirrhosis of the liver. Between 30-70% of hepatoma patients also have cirrhosis. It is estimated that a patient with cirrhosis has 40 times the chance of developing a hepatoma than a person with a healthy liver. Cirrhosis usually results from alcohol abuse or chronic viral hepatitis.
• Exposure to hepatitis B (HBV) or hepatitis C (HBC) viruses. In Africa and most of Asia, exposure to hepatitis B is an important factor; in Japan and some Western countries, exposure to hepatitis C is associated with a higher risk of developing liver cancer. In the United States, nearly 25% of patients with liver cancer have evidence of HBV infection. Hepatitis B and C are commonly found among intravenous drug abusers.