The Liver

The liver is the largest organ in the body. It is found behind the ribs on the right side of the abdomen. The liver has two parts, a right lobe and a smaller left lobe.

The liver has many important functions that keep a person healthy. It removes harmful material from the blood. It makes enzymes and bile that help digest food. It also converts food into substances needed for life and growth.

The liver gets its supply of blood from two vessels. Most of its blood comes from the hepatic portal vein. The rest comes from the hepatic artery.

Cancer is a group of many related diseases. All cancers begin in cells, the body's basic unit of life. Cells make up tissues, and tissues make up the organs of the body.

Normally, cells grow and divide to form new cells as the body needs them. When cells grow old and die, new cells take their place.

Sometimes, this orderly process goes wrong. New cells form when the body does not need them, or old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor. Tumors can be benign or malignant:

• Benign tumors are not cancer. Usually, doctors can remove them. In most cases, benign tumors do not come back after they are removed. Cells from benign tumors do not spread to tissues around them or to other parts of the body. Most important, benign tumors are rarely a threat to life.

• Malignant tumors are cancer. They are generally more serious and may be life threatening. Cancer cells can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or the lymphatic system. That is how cancer cells spread from the original cancer (the primary tumor) to form new tumors (secondary tumors) in other organs. The spread of cancer is called metastasis. Different types of cancer tend to spread to different parts of the body.

Most primary liver cancers begin in hepatocytes (liver cells). This type of cancer is called hepatocellular carcinoma or malignant hepatoma.

Children may develop childhood hepatocellular carcinoma or hepatoblastoma. This booklet does not deal with childhood liver cancer. Also, the Cancer Information Service (1-800-4-CANCER) can provide information about liver cancer in children.

When liver cancer spreads (metastasizes) outside the liver, the cancer cells tend to spread to nearby lymph nodes and to the bones and lungs. When this happens, the new tumor has the same kind of abnormal cells as the primary tumor in the liver. For example, if liver cancer spreads to the bones, the cancer cells in the bones are actually liver cancer cells. The disease is metastatic liver cancer, not bone cancer. It is treated as liver cancer, not bone cancer. Doctors sometimes call the new tumor "distant" disease.

Similarly, cancer that spreads to the liver from another part of the body is different from primary liver cancer. The cancer cells in the liver are like the cells in the original tumor. When cancer cells spread to the liver from another organ (such as the colon, lung, or breast), doctors may call the tumor in the liver a secondary tumor. In the United States, secondary tumors in the liver are far more common than primary tumors.
Liver Cancer: Who's at Risk?

Researchers in hospitals and medical centers around the world are working to learn more about what causes liver cancer. At this time, no one knows its exact causes. However, scientists have found that people with certain risk factors are more likely than others to develop liver cancer. A risk factor is anything that increases a person's chance of developing a disease.

Studies have shown the following risk factors:

• Chronic liver infection (hepatitis) -- Certain viruses can infect the liver. The infection may be chronic. (It may not go away.) The most important risk factor for liver cancer is a chronic infection with the hepatitis B virus or the hepatitis C virus. These viruses can be passed from person to person through blood (such as by sharing needles) or sexual contact. An infant may catch these viruses from an infected mother. Liver cancer can develop after many years of infection with the virus.

  These infections may not cause symptoms, but blood tests can show whether either virus is present. If so, the doctor may suggest treatment. Also, the doctor may discuss ways of avoiding infecting other people.

  In people who are not already infected with hepatitis B virus, hepatitis B vaccine can prevent chronic hepatitis B infection and can protect against liver cancer. Researchers are now working to develop a vaccine to prevent hepatitis C infection.

• Cirrhosis -- Cirrhosis is a disease that develops when liver cells are damaged and replaced with scar tissue. Cirrhosis may be caused by alcohol abuse, certain drugs and other chemicals, and certain viruses or parasites. About 5 percent of people with cirrhosis develop liver cancer.

• Aflatoxin -- Liver cancer can be caused by aflatoxin, a harmful substance made by certain types of mold. Aflatoxin can form on peanuts, corn, and other nuts and grains. In Asia and Africa, aflatoxin contamination is a problem. However, the U.S. Food and Drug Administration (FDA) does not allow the sale of foods that have high levels of aflatoxin.

• Being male -- Men are twice as likely as women to get liver cancer.

• Family history -- People who have family members with liver cancer may be more likely to get the disease.

• Age -- In the United States, liver cancer occurs more often in people over age 60 than in younger people.

The more risk factors a person has, the greater the chance that liver cancer will develop. However, many people with known risk factors for liver cancer do not develop the disease.

People who think they may be at risk for liver cancer should discuss this concern with their doctor. The doctor may plan a schedule for checkups.

Hepatocellular carcinoma (HCC) is one of the most common tumors in the world and the third most frequent cause of cancer deaths. It is more prevalent in Asia and Africa than in the U.S. or Western Europe. HCC is four times more common in men than in women and studies in Asia have demonstrated that the risk of HCC is 100 times greater in persons who have a history of hepatitis B infection. 

The most common symptoms of HCC are abdominal pain with detection of an abdominal mass in the upper right quadrant. Imaging procedures to detect liver tumors include ultrasound, CT, MRI, and hepatic artery angiography.