To help you understand what is happening when you have cancer, it helps to know how your body works normally. Our bodies are made up of tiny building blocks called cells. Normal cells grow and multiply when the body needs them and die out when the body does not need them.
Cancer is made up of abnormal cells that grow whether or not they are needed. Liver cancer is cancer that starts in the cells of the liver. Cancer that begins in the liver is called primary liver cancer. This cancer is uncommon in the United States. It is the most common cancer in some African and East Asian countries, though.
Liver cancer tends to develop in several parts of the liver at the same time. When the cancer does spread outside of the liver, it may move to the tissues close to the liver and to the diaphragm, the muscle that separates the lungs from the abdomen. It is uncommon for liver cancer to spread to lymph nodes.
Primary liver cancer is not the same as cancers that have started somewhere else in the body and have then spread to the liver. These are called liver metastases. Cancer that starts in other places, such as the colon, breast, or lung, and then spreads to the liver is called secondary liver cancer. Almost all other cancers, if they spread, can spread to the liver. Secondary liver cancer is more common in the United States than primary liver cancer. Cancer that has spread to the liver is treated like the original cancer. For instance, lung cancer that has metastasized to the liver is treated like lung cancer.
Hepatocellular carcinoma is a cancer that arises from within the liver. This is the most common liver cancer. It is also called hepatoma. About three out of every four liver cancers are of this type. This type of cancer starts in the main liver cells called hepatocytes.