Cancer is the uncontrolled growth of abnormal cells anywhere in a body. These abnormal cells are termed cancer cells, malignant cells, or tumor cells. These cells can infiltrate normal body tissues. Many cancers and the abnormal cells that compose the cancer tissue are further identified by the name of the tissue that the abnormal cells originated from (for example, breast cancer, lung cancer, colon cancer, liver cancer).
Frequently, cancer cells can break away from this original mass of cells, travel through the blood and lymph systems, and lodge in other organs where they can again repeat the uncontrolled growth cycle. This process of cancer cells leaving an area and growing in another body area is termed metastatic spread or metastasis. For example, if breast cancer cells spread to a bone, it means that the individual has “metastatic breast cancer to bone”. This is not the same as "bone cancer," which would the cancer had started in the bone.
Liver cancer is cancer that begins in the cells of your liver. Several types of cancer can form in the liver. The most common type of liver cancer is hepatocellular carcinoma, which begins in the main type of liver cell (hepatocyte). Other types of liver cancer, such as intrahepatic cholangiocarcinoma and hepatoblastoma, are much less common.
Not all cancers that affect the liver are considered liver cancer. Cancer that begins in another area of the body — such as the colon — and then spreads to the liver is called “metastatic colon cancer to liver” rather than “liver cancer”. Cancer that spreads to the liver is more common than cancer that begins in the liver cells.