A Silent Disease
Cholangiocarcinoma (bile duct cancer) is often labeled a silent disease because many times the signs and symptoms can go unnoticed until the cancer is in the advanced stage. Even when there are early signs and symptoms, they may be vague and easily attributed to another disease. Surgery offers the best treatment results when the disease is found at an early stage, before it has spread. Because cholangiocarcinoma is usually found in an advanced stage (after it has spread), often times surgery to remove the cancer is not an option.
Cholangiocarcinoma starts in the bile duct, a thin tube, about 4 to 5 inches long, that reaches from the liver to the small intestine. The major function of the bile duct is to move a fluid called bile from the liver and gallbladder to the small intestine, where it helps digest the fats in food.
Different parts of the bile duct system have different names. In the liver it begins as many tiny tubes (ductules) where bile collects from the liver cells. The ductules come together to form small ducts, which then merge into larger ducts and eventually the left and right hepatic ducts. The ducts within the liver are called intrahepatic bile ducts. These ducts exit from the liver and join to form the common hepatic duct at the hilum. About one-third of the way along the length of the bile duct, the gallbladder (a small organ that stores bile) attaches by a small duct called the cystic duct. The combined duct is called the common bile duct. The common bile duct passes through part of the pancreas before it empties into the first part of the small intestine (the duodenum), next to where the pancreatic duct also enters the small intestine.
Cancers can develop in any part of the bile duct and, based on their location, are classified into 3 types:
- Intrahepatic bile duct cancers
- Perihilar (also called hilar) cholangiocarcinoma
- Distal bile duct cancers.
Cancers in these different areas may cause different symptoms.
Intrahepatic cholangiocarcinoma develops in the smaller bile duct branches inside the liver. It can sometimes be confused with cancer that starts in the liver cells, which is called hepatocellular carcinoma, and is often treated the same way. Only about 1 in 10 cholangiocarcinomas are intrahepatic.
Perihilar (also called hilar) cholangiocarcinomas develop at the hilum, where the hepatic ducts have joined and are just leaving the liver. They are also called Klatskin tumors. These are the most common type of bile duct cancer, making up 6 or 7 of every 10 bile cholangiocarcinomas.. These cancers are grouped with distal bile duct cancers as extrahepatic bile duct cancers.
Distal cholangiocarcinomas are found further down the bile duct, closer to the small intestine. Because these bile ducts are outside of the liver, these cancers are grouped with perihilar cancers as extrahepatic cholangiocarcinoma. Distal cholangiocarcinomas make up 2 to 3 of every 10 bile duct cancers.
Cholangiocarcinoma can also be divided into types based on how the cancer cells look under the microscope. More than 95% of bile duct cancers are carcinomas and most are adenocarcinomas. Adenocarcinomas are cancers of glandular cells that can develop in several organs of the body. Bile duct adenocarcinomas develop from the mucous glands that line the inside of the duct. Cholangiocarcinoma is another name for a bile duct carcinoma.
Adapted from National Institutes of Health: http://www.cancer.gov/