What is Liver Cancer?

This is the first article in the Understanding Liver Cancer Guide. This guide was developed by the HealthTree Education Team and was last updated and reviewed on June 20, 2026

Cancer begins when cells in the body start to grow out of control. Liver cancer starts in the cells of the liver. The liver is a large organ that sits in the upper right part of the abdomen, behind the lower ribs. When you have liver cancer, cells in the liver do not follow the normal cell cycle. Healthy cells grow, copy themselves, and then die. Cancer cells change, grow faster than normal, and do not die the way they should.

It is important to understand the difference between cancer that starts in the liver and cancer that spreads to the liver from another organ. Cancer that starts in the liver is called primary liver cancer. Cancer that starts somewhere else and travels to the liver is called secondary liver cancer, or metastatic cancer. This guide is about primary liver cancer.

What is the liver?

The liver performs hundreds of tasks that are essential to life. Some of its most important jobs include:

• Filtering the blood to remove harmful substances, bacteria, and old blood cells
• Making bile, a fluid that helps the body digest fats and absorb vitamins
• Producing proteins the body needs for blood clotting and other functions
• Storing energy in the form of glycogen and releasing glucose into the blood when the body needs fuel
• Processing nutrients absorbed from the digestive system

Because the liver does so many important things, liver cancer can cause a wide range of symptoms and complications. It can also make some treatments more difficult if liver function is already reduced by an underlying liver disease.

How liver cancer starts

Most liver cancers develop over a long period of time in a liver that has been damaged. Chronic damage to the liver causes healthy cells to die and be replaced with scar tissue. This scarring is called fibrosis. When fibrosis becomes widespread and changes the structure of the liver, it is called cirrhosis. Cirrhosis greatly increases the risk of liver cancer because the liver cells must work harder to replace lost cells, and they are more likely to develop genetic changes that can lead to cancer.

Certain viruses and other conditions that damage the liver over many years are the most important known causes of hepatocellular carcinoma. Researchers continue to study how liver cell damage leads to the specific gene changes that cause cancer.

How does liver cancer affect the body?

As liver cancer grows, it can affect many parts of the body:

How liver cancer affects the liver

Liver cancer can reduce the liver's ability to filter blood, produce proteins, and carry out its other functions. As the tumor grows, it can cause pain in the upper right abdomen, a swollen belly, jaundice, and other symptoms related to reduced liver function.

How liver cancer affects the blood vessels

The liver has a rich blood supply from two sources, the portal vein and the hepatic artery. Liver tumors, especially hepatocellular carcinoma, tend to grow blood vessels of their own and can invade nearby blood vessels. This can lead to complications and affects which treatments are possible.

How liver cancer affects the lymph nodes and other organs

Liver cancer can spread to lymph nodes near the liver and to other organs. When liver cancer spreads, it most often goes to the lungs, bones, and the lining of the abdomen. Spread to other parts of the body is called metastasis.

Learn more about the signs and symptoms of liver cancer.

Types of liver cancer

Several types of cancer can start in the liver. The most important ones are:

• Hepatocellular carcinoma. This is by far the most common type of primary liver cancer in adults, making up about 75 to 85 percent of cases. It starts in hepatocytes, which are the main type of liver cell. Hepatocellular carcinoma almost always develops in a liver that is already damaged by cirrhosis or chronic viral hepatitis.
• Intrahepatic cholangiocarcinoma. This type of liver cancer starts in the bile ducts inside the liver. It accounts for about 10 to 15 percent of primary liver cancers. It is also called intrahepatic bile duct cancer.
• Hepatoblastoma. A rare liver cancer that occurs almost exclusively in young children, usually under three years of age.
• Angiosarcoma and hemangiosarcoma. Very rare cancers that begin in the blood vessels of the liver. They tend to grow quickly.
• Secondary liver cancer. Cancer that starts in another organ, such as the colon, breast, or lung, and spreads to the liver. This is much more common than primary liver cancer but is not the focus of this guide.

Related conditions

Certain conditions are closely linked to liver cancer and are important to understand:

• Cirrhosis. Widespread scarring of the liver caused by long-term liver damage. Cirrhosis greatly increases the risk of hepatocellular carcinoma. Any cause of cirrhosis, including hepatitis B, hepatitis C, heavy alcohol use, and nonalcoholic fatty liver disease, raises the risk of liver cancer.
• Chronic hepatitis B infection. A long-term infection with the hepatitis B virus that can cause liver inflammation and damage over many years. It is one of the leading causes of hepatocellular carcinoma worldwide, even in people who have not yet developed cirrhosis.
• Chronic hepatitis C infection. A long-term infection with the hepatitis C virus that causes liver inflammation and, over time, can lead to cirrhosis and liver cancer.
• Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. Conditions in which fat builds up in the liver, sometimes causing inflammation and scarring. These conditions are becoming more common as rates of obesity and type 2 diabetes rise, and they are an increasingly important risk factor for liver cancer.
• Aflatoxin exposure. Aflatoxins are cancer-causing substances produced by certain molds that can grow on corn, peanuts, and other foods, particularly in parts of Africa and Asia. Aflatoxin exposure is a major risk factor for liver cancer in some parts of the world.