Overview

What is cancer?

Cancer is the uncontrolled growth of cells in an organ, such as the lung, colon or skin. Cancer cells grow together to form a mass called a tumor. Benign (non-cancerous) cells can also grow and spread, but are not invasive. Cancer can be life threatening, because malignant cells can invade surrounding tissue and spread, or metastasize, to other parts of the body. Early detection before the cancer spreads provides the best chance of cure.

What is liver cancer?

The liver is a cone shaped organ that lies right under your ribs on your right side. It is the largest organ in the body and is responsible for filtering most of the toxins out of your body. It also processes and stores many of the nutrients absorbed from the intestine, makes some of the clotting factors that help stop bleeding from a cut or injury, and secretes bile into the intestine to help break down fats.

Since the liver has several functions, there are several different types of cells in the liver, so different types of tumors are found there. Each is treated differently. Your prognosis depends on the type of tumor you have.

Benign tumors

Benign tumors aren't cancerous and usually don't cause symptoms, so they don't need treatment unless they bleed. Then they need to be removed by surgery.

Malignant tumors

The most common type of cancer that begins in the liver is called hepatocellular carcinoma (HCC). It begins in the hepatocytes, which are the main type of liver cells. About 90 percent of primary liver cancers are HCCs. (A primary liver cancer is one that begins in the liver as opposed to a malignancy that has spread there (metastasize) to the liver from a cancer elsewhere in the body.)

There are three growth patterns for HCC:

• HCC usually begins as a single tumor that grows by expanding. It spreads to other parts of the liver only in later stages of the cancer. It is usually seen in people infected with the hepatitis B virus (HBV) or the hepatitis C virus (HCV).
• A second type of HCC spreads tentacle-like growths through the liver right from the beginning. It's the most common pattern seen in the United States and is most often seen in people with cirrhosis of the liver.
• The third type of HCC is called "multifocal," meaning the cancer begins as nodules within different parts of the liver.

Cholangiocarcinoma is cancer that arises from cells in the bile ducts -- tubes that carry bile to the gallbladder -- within the liver or right outside of the liver. It accounts for about 10 percent to 20 percent of liver cancers. Cholangiocarcinomas are usually first discovered on radiological studies and diagnosed by biopsy.

You have a higher risk of developing cholangiocarcinoma if you have gallstones or gallbladder inflammation, chronic ulcerative colitis, or a chronic infection with certain types of parasitic worms found in parts of Asia, such as liver flukes (Fasciola hepatica).

Angiosarcomas and hemangiosarcomas

Angiosarcomas and hemangiosarcomas are rare cancers that begin in blood vessels of the liver. People who have been exposed to vinyl chloride -- a chemical used in manufacturing plastics -- are likely to develop these cancers. Also, people exposed to thorium dioxide (Thorotrast), which was injected into people who had certain x-ray tests, are at risk for developing these rare cancers. Thorium dioxide hasn't been used in medical settings for about 50 years. And workers' exposure to vinyl chloride is very strictly regulated.

Other causes of these types of liver cancers are linked to exposure to arsenic or radium, or to a hereditary condition known as hemochromatosis. In about half of all cases, however, no likely cause can be identified.

Hepatoblastoma

Hepatoblastoma is a very rare kind of cancer that develops in children, usually younger than 4 years old. About 70 percent of children with this disease are treated successfully with surgery and chemotherapy. The survival rate is over 90 percent for early stage hepatoblastomas.

Secondary cancer site

Most of the time when cancer is found in the liver, it's as a secondary cancer site. Secondary liver cancer is common for primary malignant tumors that originated in the lung, colon, breast, etc. and spread to the liver.

More on Liver Cancer

In the Encyclopedia:

This article was reviewed and updated June 2007.