• Infection or inflammation of your bile ducts over many months or years (sclerosing cholangitis).
  
   
• One in three people who have the cancer also have gallstones. However, very few people with gallstones get bile duct cancer, and there is no proven link.
  
   
• Non-cancerous cysts in your bile duct. These are called choledochal cysts and about one in 25 may develop into a cancer.
  
   
• Being born with widened bile ducts leading from your liver (dilated hepatic ducts). It is a rare condition, and seems to increase the risk of bile duct cancer for between one in 10 and one in 20 people.
  
   
• Rarely, when you have inflammation of the bowel for a long time.
  
   
• Environmental pollution. Certain chemicals have been associated with a big increase in bile duct cancers over the last 30 years. These chemicals include dioxins released by organochlorines (from plastics and pesticides), which are fat-soluble and can build up in the body. Some food preservatives, PCBs (polychlorinated biphenyls, from fluids used in electrical transformers) and nitrates (used in farming) are also regarded as potentially dangerous. It is believed that because the bile ducts are a waste-pipe for the liver, they may be particularly sensitive to this toxic load.
  
   
• It is three times more common in men than in women.

There is no evidence that bile duct cancer can be inherited. This means that other members of your family do not have an increased risk of getting it.