Liver cancer is cancer that begins in the cells of your liver. Your liver is a football-sized organ that sits in the upper right portion of your abdomen, beneath your diaphragm and above your stomach.
The most common form of liver cancer is hepatocellular carcinoma, which begins in the main type of liver cell (hepatocyte). Other types of cells in the liver can develop cancer, but these 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, lung or breast — and then spreads to the liver is called metastatic cancer rather than liver cancer. And this type of cancer is named after the organ in which it began — such as metastatic colon cancer to describe cancer that begins in the colon and spreads to the liver.