What Is Liver Cancer

What Is Liver Cancer?
Liver cancer is a type of 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 and function of the liver.

The liver
The liver is the largest internal organ. It lies under your right ribs just beneath your right lung. It has two lobes (sections).


illustration showing the right and left lobes of the liver in relation to the hepatic bile duct, pancreas, gallbladder and small intestine with a detailed view of liver lobule, hepacytes (liver cells), sinusoid, canaliculus, portal vein, hepatic artery, bile duct and central vein
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 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 intestine that your body needs to function. 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 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 a different prognosis (outlook).

Primary liver cancer
A cancer that starts in the liver is called primary liver cancer. There is more than one kind of primary liver cancer.

Hepatocellular carcinoma (HCC)
This is the most common form of liver cancer in adults.

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 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.
Doctors can classify 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. It is rare, making up less than 1% of HCCs and is most often seen in women younger than age 35. Often the rest of the liver is not diseased. This subtype tends to have a better outlook than other forms of HCC.

Most of the rest of this content refers only to hepatocellular carcinoma and is called