Cholangiocarcinoma, also known as bile duct cancer, is a rare and aggressive type of cancer that forms in bile ducts. Bile ducts are thin tubes that carry a digestive fluid called bile from your liver to other digestive organs.
In cholangiocarcinoma, a gene in the cells lining the bile duct changes abnormally, causing the cells to grow and divide without stopping. These cancer cells form tumors. Over time, some cells can break off and spread to other parts of the body. This is called metastasis.