Liver cancer is a cancer that starts in the liver. Tounderstand liver cancer, it helps to know about the normal structure and function of the liver.

About the liver

The liver is the largest internal organ. It lies under your right ribs just beneath your right lung. If you were to poke your fingers up under your right ribs, you could almost touch it.

It is shaped like a pyramid and divided into right and left lobes. The lobes are further divided into segments. Unlike most other organs, the liver gets blood from 2 sources: the hepatic artery supplies the liver with blood rich in oxygen from the heart, and the portal vein carries nutrient-rich blood from the intestines.

You cannot live without your liver. It has several important functions:

• It breaks down and stores many of the nutrients absorbed from the intestine that your body needs to function. Some nutrients must be changed (metabolized) in the liver before they can be used by the rest of the body for energy or to build and repair body tissues.

• It makes most of the clotting factors that keep the body from bleeding too much when you are cut or injured.

• It secretes bile into the intestines to help absorb nutrients (especially fats).

• It plays an important role in removing toxic wastes from the body.

The liver is made up of several different types of cells. This is why several types of malignant (cancerous) and benign (non-cancerous) tumors can form in the liver. These tumors have different causes, are treated differently, and have a different prognosis (outlook for health or recovery).

Benign tumors

Benign tumors sometimes grow large enough to cause problems, but they do not grow into nearby tissues or spread to distant parts of the body. If they need to be treated, the patient can usually be cured with surgery.

Hemangiomas

The most common type of benign liver tumor, hemangiomas start in blood vessels. Most hemangiomas of the liver cause no symptoms and do not need treatment. But some may bleed and need to be removed surgically.

Hepatic adenomas

These are benign tumors that start from hepatocytes (the main type of liver cell). Most cause no symptoms and do not need treatment. But some eventually cause symptoms, such as pain or a mass in the abdomen (stomach area) or blood loss. Because there is a risk that the tumor could rupture (leading to severe blood loss) and a small risk that it could eventually develop into liver cancer, most experts usually advise surgical removal if possible.

The use of certain drugs may increase the risk of getting these tumors. Women have a higher chance of having one of these tumors if they take birth control pills, although this is a rare complication. Stopping the pills can sometimes cause the tumor to shrink. Men who use anabolic steroids may also develop these. Adenomas may shrink when the drugs are stopped.

Focal nodular hyperplasia

Focal nodular hyperplasia (FNH) is a tumor-like growth of several cell types (hepatocytes, bile duct cells, and connective tissue). Although FNH tumors are benign, it can be hard to tell them apart from true liver cancers, and doctors sometimes remove them when the diagnosis is unclear. If you have symptoms from an FNH tumor, it can be surgically removed and you can be cured.

Both hepatic adenomas and FNH tumors are more common in women than in men.

Cancerous tumors that start in the liver

Several types of cancer can start in the liver.

Hepatocellular carcinoma (HCC) or hepatocellular cancer

This is the most common form of liver cancer in adults. It is also sometimes called hepatoma because it comes from the hepatocytes (the main type of liver cell). About 3 out of 4 cancers that start in the liver are this type.

Hepatocellular cancers can have different growth patterns:

• Some begin as a single tumor that grows larger. Only late in the disease does it spread to other parts of the liver.

• A second type seems to start as many smaller cancer nodules throughout the liver -- not just a single tumor. This is seen most often in people with cirrhosis (chronic liver damage) and is the most common pattern seen in the United States.

Under a microscope, doctors can distinguish several subtypes of HCC. Most often these subtypes do not affect treatment or prognosis (outlook). But one of these subtypes, fibrolamellar, is important to recognize. This type is rare, making up less than 1% of HCCs.  The patients with this type are usually younger (below age 35), and the rest of their liver is not diseased. This subtype has a much better outlook than other forms of HCC.

Intrahepatic cholangiocarcinomas (bile duct cancers)

About 10% to 20% of cancers that start in the liver are intrahepatic cholangiocarcinomas. They start in the small bile ducts (tubes that carry bile to the gallbladder) within the liver. (Most cholangiocarcinomas actually start in the bile ducts outside the liver.)

Although the rest of this document deals mainly with hepatocellular cancers, cholangiocarcinomas are often treated the same way. For more detailed information on this type of cancer, see the separate American Cancer Society document, Bile Duct (Cholangiocarcinoma) Cancer.

Angiosarcomas and hemangiosarcomas

These are rare cancers that begin in blood vessels of the liver. People who have been exposed to vinyl chloride or to thorium dioxide (Thorotrast) are more likely to develop these cancers. See the section "What are the risk factors for liver cancer?" Other cases are thought to be due to exposure to arsenic or radium, or to an inherited condition known as hemochromatosis. In about half of all cases, no likely cause can be identified.

These tumors grow quickly and are usually too widespread to be removed surgically by the time they are found. Chemotherapy and radiation therapy may help slow the disease, but most patients do not live more than a year after the diagnosis.

Hepatoblastoma

This is a very rare kind of cancer that develops in children, usually in those younger than 4 years old. The cells of hepatoblastoma are similar to fetal liver cells. About 70% of children with this disease are treated successfully with surgery and chemotherapy, and the survival rate is greater than 90% for early-stage hepatoblastomas.

Secondary liver cancer

Most of the time when cancer is found in the liver it did not start there but has spread (metastasized) from somewhere else in the body, such as the pancreas, colon, stomach, breast, or lung. These tumors are named and treated based on their primary site (where they started). For example, cancer that started in the lung and spread to the liver is called lung cancer with spread to the liver, not liver cancer. In the United States and Europe, secondary (metastatic) liver tumors are more common than primary liver cancer. The opposite is true for many areas of Asia and Africa.

For more information on liver metastases from different types of cancer, refer to the American Cancer Society documents on these cancer types, and to our document, Advanced Cancer.

Most of the remaining content in this document refers only to hepatocellular cancer.

Last Medical Review: 11/05/2009
Last Revised: 11/05/2009