What are biliary tract cancers?

Biliary tract cancers start in cells of either the gallbladder or bile duct. A cancerous (malignant) tumour is a group of cancer cells that can grow into nearby tissue and destroy it. These cancer cells can also spread (metastasize) to other parts of the body. When cancer starts in gallbladder cells, it is called primary gallbladder cancer. When cancer starts in bile duct cells, it is called primary bile duct cancer.

The gallbladder and bile ducts are part of the digestive system. Together, they are called the biliary system or biliary tract. Your liver makes bile, which is a yellow-green fluid that helps your body digest fats. The biliary tract is responsible for storing, concentrating (by absorbing water) and transporting bile from the liver to the small intestine for digestion.

Cells of the biliary tract sometimes change and no longer grow or behave normally. These changes may lead to non-cancerous (benign) conditions, such as inflammation of the gallbladder (cholecystitis) or gallstones. The changes can also lead to non-cancerous tumours, such as adenomas or polyps.

But in some cases, changes to the biliary tract cells can cause cancer. Most often, biliary tract cancers start in the epithelial cells of the inner walls of the gallbladder or bile duct. This type of cancer is called adenocarcinoma of the gallbladder or bile duct. Adenocarcinoma makes up about 90% of all biliary tract cancers.

Other rarer types of biliary tract cancer can also develop. These include squamous cell carcinoma (SCC), sarcoma and lymphoma.