Your liver is a football-sized organ that sits in the upper right portion of
your abdomen, beneath your diaphragm and above your stomach. Your liver
processes most of the nutrients absorbed from your small intestine and
determines how much sugar (glucose), protein and fat enter your bloodstream. It
also manufactures blood-clotting substances and certain proteins. Your liver
performs a vital detoxifying function by removing drugs, alcohol and other
harmful substances from your bloodstream.
Liver cancer occurs when liver cells begin to grow abnormally. It's not
completely understood why this happens, but researchers believe that cancer
starts with damage to DNA — the material that contains the instructions for
every chemical process in your body, including the rate of cellular growth. DNA
damage causes changes in these instructions. One result is that cells may begin
to grow out of control and eventually form a tumor — a mass of malignant cells.
Primary liver cancer
Primary liver cancer is divided into several types based on the type of cells
that become cancerous. Types include:
- Hepatocellular carcinoma (HCC). This is the
most common form of primary liver cancer in both children and adults. It starts
in the hepatocytes, the main type of liver cell.
- Cholangiocarcinoma. This type of cancer
begins in the small tube-like bile ducts within the liver. This type of cancer
is sometimes called bile duct cancer.
- Hepatoblastoma. This rare type of liver
cancer affects children younger than 4 years of age. Most children with
hepatoblastoma can be successfully treated.
- Angiosarcoma or hemangiosarcoma. These rare
cancers begin in the blood vessels of the liver and grow very quickly.
Metastatic cancer
In the United States, most cancer found in the liver has spread there from
another part of the body. Rather than being referred to as liver cancer, this
type of cancer is usually named after the organ where it originated and is
described as "metastatic." For instance, cancer that has spread to the liver
from the colon is referred to as metastatic colon cancer.
Metastatic cancers form when malignant cells detach from the primary cancer and
travel through the body in the circulatory or lymphatic system. Cancers that
begin in certain organs near the liver, such as the pancreas, can spread
directly to the liver. Most metastatic cancers reach the liver through the
bloodstream. Why the liver is so commonly affected by metastatic cancer isn't
clear. One reason may be the liver's rich blood supply.