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Liver cancer is cancer that starts in the liver. Cancer starts when cells in the body begin to grow out of control. To learn more about how cancers start and spread, see What Is Cancer?

To understand liver cancer, it helps to know about the normal structure of the liver and what the liver does.

About the liver

The liver is a large internal organ that is under your right ribs just beneath your right lung. It has two lobes (sections).

The liver is made up mainly of cells called hepatocytes. It also has other types of cells, including cells that line its blood vessels and cells that line small tubes in the liver called bile ducts. The bile ducts carry a digestive fluid called bile from the liver to the gallbladder or directly to the intestines.

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

• It breaks down and stores many of the nutrients absorbed from the intestines that your body needs. Some nutrients must be changed (metabolized) in the liver before they can be used for energy or to build and repair body tissues.
• It makes most of the clotting factors that keep you from bleeding too much when you are cut or injured.
• It delivers bile into the intestines to help the body break down and absorb nutrients (especially fats).
• It breaks down alcohol, drugs, and toxic wastes in the blood, which then pass from the body through urine and stool.

The different types of cells in the liver can form several types of malignant (cancerous) and benign (non-cancerous) tumors. These tumors have different causes, are treated differently, and have different prognoses (outlooks).

Primary liver cancer

A cancer that starts in the liver is called primary liver cancer. There are different types of primary liver cancer.

Hepatocellular carcinoma (HCC)

This is the most common form of liver cancer in adults.

Hepatocellular cancers can grow in different ways:

• Some begin as a single tumor that grows larger. Later, it can spread to other parts of the liver.
• Some start out as many small 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.

Most of the rest of this information is about hepatocellular carcinoma and will be referred to as liver cancer.

Intrahepatic cholangiocarcinoma (bile duct cancer)

About 10% to 20% of liver cancers start in the cells that line the small bile ducts (tubes that carry bile to the gallbladder). These are called intrahepatic cholangiocarcinomas (bile duct cancers). Most cholangiocarcinomas, however, start in the bile ducts outside the liver.

Although the rest of this information is mainly about hepatocellular cancers, intrahepatic cholangiocarcinomas are often treated the same way. For more, see What Is Bile Duct Cancer?

Fibrolamellar carcinoma

Fibrolamellar carcinoma (FLC) was once considered a subtype of HCC, but it’s now thought of as a separate type of liver cancer. It is rare, and it most often develops in women younger than age 35 (although it can also occur in older people). Often the rest of the liver is not diseased.

FLC is more likely to be removable by surgery than HCC.

Angiosarcoma and hemangiosarcoma

These are rare cancers that begin in cells that line the blood vessels in the liver. People who have been exposed to vinyl chloride or to thorium dioxide (Thorotrast) are more likely to develop these cancers (see Liver Cancer Risk Factors). The risk of these cancers is also increased by exposure to arsenic or radium and by a condition known as hereditary hemochromatosis (a genetic disorder of iron absorption). In about half of these cancers, no likely cause can be identified.

These tumors grow quickly and are usually too widespread to be removed with surgery by the time they are found. Chemotherapy and radiation therapy might help slow the disease, but it’s usually hard to treat. These cancers are treated like other sarcomas. For more information, see What Is Soft Tissue Sarcoma?

Hepatoblastoma

This is a very rare cancer that develops in children, usually in those younger than 4 years old. The cells of hepatoblastoma are like fetal liver cells. About 2 out of 3 children with these tumors are treated successfully with surgery and chemotherapy, although the tumors are harder to treat if they have spread outside the liver.

Secondary liver cancer

Most often when cancer is found in the liver, it didn’t start there. Many cancers that start somewhere else in the body, such as the pancreas, colon, stomach, breast, or lung, can spread (metastasize) to the liver. Cancer that has spread from its original (primary) site to the liver is sometimes called a secondary liver cancer.

These cancers are treated based on where they started. For example, cancer that started in a lung and spread to the liver is considered lung cancer, not liver cancer, and it is treated as lung cancer.

In the United States and Europe, secondary (metastatic) liver tumors are more common than primary liver cancer. The opposite is true for many parts of Asia and Africa.

For more on liver metastases from different types of cancer, see the specific cancer type, as well as Advanced Cancer.

Benign liver tumors

Benign (non-cancer) liver tumors sometimes grow large enough to cause problems, but they don’t grow into nearby tissues or spread to distant parts of the body. If they need to be treated, they can usually be cured with surgery.

Hemangioma

The most common benign liver tumors, hemangiomas, start in cells lining blood vessels. Most liver hemangiomas don’t cause symptoms and don’t need treatment. But if they bleed or cause other problems, they may need to be removed with surgery.

Hepatic adenoma

Hepatic adenoma is a benign tumor that starts from hepatocytes (the main type of liver cell).

Most of these tumors don’t cause symptoms and don’t need treatment. Some eventually cause symptoms, such as pain or a lump in the abdomen (belly) or blood loss.

Doctors often advise surgery to remove the tumor, if possible, because there’s a risk that the tumor could rupture (leading to severe blood loss), as well as a small risk that it could eventually develop into liver cancer.

These tumors are more common in women than in men. Women have a higher chance of having one of these tumors if they take birth control pills, although this is rare. Men who use anabolic steroids may also develop these tumors. Adenomas may shrink when these drugs are stopped.

Focal nodular hyperplasia

Focal nodular hyperplasia (FNH) is a tumor-like growth made up of several cell types (hepatocytes, bile duct cells, and connective tissue cells). Although FNH tumors are benign, they might cause symptoms. It can be hard to tell them apart from true liver cancers, so doctors sometimes remove them when the diagnosis is unclear. FNH tumors are more common in women than in men.