The liver is the body's largest internal organ. It is located in the upper right-hand side of the abdomen and weighs about 2-3 pounds. The liver is responsible for several essential body functions, such as:
- Filtering and breaking down harmful substances from the blood to be removed from the body in urine and stools
- Making bile that helps digest food, especially fat
- Storing glycogen, which is used for energy
- Converting nutrients from the food we eat into essential blood components
- Regulating blood clotting
- Maintaining hormone balances
- Storing some vitamins
- Making factors that help the immune system fight infection
- Removing bacteria from the blood
Liver cancer is the unregulated growth of cells in the liver. Cells that grow out of control can form solid tumors in the liver. Some liver tumors are benign, or non-cancerous, and they may enlarge but do not spread. Cancerous tumors can spread (metastasize) to nearby tissues or other parts of the body.
- When the cancer starts in the liver, it's known as primary liver cancer. This type is relatively rare in the U.S. The most common type of primary liver cancer arises from the main cells in the liver, the hepatocytes, and is called hepatocellular carcinoma (HCC). Less commonly, primary liver cancers can arise from cells of the bile ducts in the liver (cholangiocytes), which is called cholangiocarcinoma. In children, primary liver cancer can arise from immature liver cells (called hepatoblasts), which is called hepatoblastoma.
- More commonly, cancer starts elsewhere in the body and spreads, or metastasizes, to the liver. Cancer that originates in one part of the body but then spreads to the liver is not known as "liver cancer" but typically keeps the name of its site of origin. For example, metastatic breast or lung cancer is still considered "breast" or "lung" cancer—and is treated accordingly—even if it spreads to the liver, because it originated in the breast or lung.
Primary liver cancer and cancer that has spread to the liver are diagnosed and treated differently. This article focuses on primary liver cancer.
Liver cancer is one of the leading causes of cancer deaths globally, resulting in more than 700,000 deaths per year. It is more common in sub-Saharan Africa and Southeast Asia. In the United States, the rate of liver cancer has more than tripled since 1980, while deaths from liver cancer have more than doubled during the same time period. The American Cancer Society estimates that around 42,000 new cases of liver cancer are diagnosed annually in the United States, and about 30,000 people die from liver cancer each year.
Liver cancer can be hard to recognize and diagnose until it has progressed and caused significant liver damage and affected liver function. Most people don't have any signs or symptoms in the early stages. The symptoms that may appear later can be vague and non-specific, meaning that they can occur with other conditions.
Because liver cancer is typically identified at a later stage, the outlook (prognosis) is often poor. According to the Centers for Disease Control and Prevention, before liver cancer metastasizes, the 5-year survival rate is 26%, but once the cancer spreads to nearby tissues, the survival rate drops to 10%. When the liver cancer has spread to distant organs, the 5-year survival rate is just 4%. Your healthcare practitioner may monitor you or test for liver cancer if you have a higher risk of developing the disease.
There are two main types of liver cancer:
- Hepatocellular carcinoma (HCC)—the most common form of primary liver cancer; this type of cancer can start as a single tumor that grows larger without affecting the rest of the liver until late in the disease, or it can begin as many small cancer nodules throughout the organ. Both forms are most prevalent in people with cirrhosis (chronic liver damage).
There are several subtypes of HCC, but they typically have similar treatments and outlooks. One exception is the rare subtype fibrolamellar, which makes up less than 1% of HCC cases. This subtype, which often has a better outlook than other forms of HCC, is most common in women younger than age 35.
- Bile duct cancer (intrahepatic cholangiocarcinoma)—cancer that starts in the cells that line the bile ducts inside the liver; this accounts for 10% to 20% of cancers that start in the liver and is the third-leading cause of cancer-related deaths globally.
Other rare types of liver cancer include:
- Angiosarcoma and hemangiosarcoma—cancers that begin in the cells that line the blood vessels of the liver
- Hepatoblastoma—a very rare type of cancer that develops in children, usually younger than 4 years old