The liver is located in the right abdomen, above the stomach. It is the largest internal organ in the human body, and it performs several important functions. One of its main jobs is to produce bile, a thick fluid that helps the body digest fats. The liver also removes toxins from the bloodstream, processes and stores nutrients absorbed from the intestines, and produces clotting factors that help stop bleeding from a cut or injury.
There are two broad categories of liver cancer — tumors that originate in the liver itself (primary liver cancer) and cancer that has spread to the liver from other parts of the body (secondary, or metastatic liver cancer).
Primary Liver Cancer
More than 24,000 new cases of primary liver cancer are diagnosed in the U.S. every year. Most primary liver tumors are the result of chronic liver disease, usually cirrhosis (irreversible scarring of the liver) or chronic viral hepatitis (long-term inflammation of the liver caused by hepatitis B or hepatitis C infection). Other diseases that raise a person’s risk of liver cancer include fatty liver disease and rare metabolic/storage diseases.
Over the last 20 years, primary liver cancer has become much more common in the United States, mainly because of the spread of chronic viral hepatitis. Men are more than twice as likely as women to develop this cancer.
Unfortunately, patients with primary liver cancer often do not experience any symptoms until the disease is at an advanced stage. The first, and sometimes only, sign of a liver tumor is jaundice, a yellow discoloration of the skin and whites of the eyes caused by high levels of bile pigment (bilirubin) in the blood. Other possible symptoms include abdominal pain, weight loss and ascites (fluid accumulation in the abdomen).
Because the liver is made up of different types of cells, several types of cancer can form within the liver. The most common forms of primary liver cancer are:
Hepatocellular carcinoma (HCC) — a primary cancer that begins in the hepatocytes, the cells that make up the main functional part of the liver. Approximately three out of four primary liver cancers are HCCs. (This form of cancer is sometimes referred to as “hepatoma.”) Some HCCs begin as a single tumor that grows and later spreads to other parts of the liver. In other cases, HCC begins as many small tumors scattered throughout the organ. This cancer may spread elsewhere in the body.
Cholangiocarcinoma — a cancer that starts in the bile ducts - the tubes that connect the liver and the gallbladder to the small intestine. About 10 to 20 percent of primary liver cancers are cholangiocarcinomas. These tumors are classified as:
Intrahepatic — tumors that arise from the bile duct system that is inside the liver.
Extrahepatic — tumors that arise in the part of the biliary system outside the liver. About 90 percent of bile duct tumors fall in this category. (For more information about extrahepatic cholangiocarcinoma, see Bile Duct Cancer.)
There are also several kinds of non-cancerous tumors that can arise in the liver, including hemangiomas, adenomas and cysts. Some of these carry a risk of becoming a cancer. To learn more about these benign abnormalities, visit our Liver/Pancreas/Bile Duct section.
Metastatic Liver Cancer
Most liver tumors are cancers that have spread (or metastasized) to the liver from other parts of the body. The most common source of liver metastases is colorectal cancer. Other frequent sources are cancers of the breast, stomach and pancreas, and neuroendocrine tumors.
Patients with metastatic liver cancer frequently do not experience any symptoms related to their liver tumor. When symptoms do arise, they can include jaundice and other common indications of liver disease.
Liver Cancer Diagnosis
Physicians use a variety of tests to diagnose liver cancer and determine the extent of a patient’s disease.
CT and MRI imaging may be used to determine the number, size and location of liver tumors and to find out if the cancer has spread outside the liver.
Blood tests are used to evaluate the overall health of a patient’s liver and also to detect proteins that can indicate the presence of liver cancer.
Needle biopsy may be performed to obtain a small sample of liver tissue to test for the presence of liver cancer cells. Local anesthesia is used to numb the skin where a needle is inserted through the skin. Ultrasound or CT imaging guides the biopsy of the liver.
To find out more about advanced diagnostic techniques available at Froedtert & The Medical College of Wisconsin, read Imaging the Liver, Pancreas and Bile Ducts.