Cancer is an uncontrolled overgrowth of cells. The bile ducts or biliary tree is a series of channels that carry bile produced by the liver cells (hepatocytes) from the liver cells till the ampulla where it empties into the small intestine. This includes the bile ducts, the right and left hepatic duct which converges to form the main hepatic duct, the gall bladder, the cystic duct and the common bile duct. Any cancerous growth that arises from the cells of the bile ducts is called bile duct cancer. It is a relatively rare cancer that occurs mostly in people older than 50.