The bile ducts are the tubes connecting the liver and gall bladder to the small intestine (small bowel). Bile is a fluid made by the liver and stored in the gall bladder. Its main function is to break down fats during their digestion in the small bowel. In people who have had their gall bladder removed, bile flows directly into the small intestine. The bile ducts and gall bladder are known as the biliary system. [ Diagram showing the position of the bile duct ]Cancer is classified according to the type of cell from which it starts. Cancer of the biliary system almost always starts in a type of tissue called glandular tissue and is then known as adenocarcinoma. If the cancer starts in the part of the bile ducts contained within the liver it is known as intra-hepatic. If it starts in the area of the bile ducts outside the liver it is known as extra-hepatic. This information concentrates mainly on extra-hepatic bile duct cancers. Intra-hepatic bile duct cancers may be treated like primary liver cancer.