Cancer is a group of many related diseases. All cancers begin in cells
, the body's basic unit of life. Cells make up tissues, and tissues make up the organs of the body.
Normally, cells grow and divide to form new cells as the body needs them. When cells grow old and die, new cells take their place.
Sometimes this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor
Tumors can be benign or malignant.
Benign tumors are not cancer.
Usually, doctors can remove them. Cells from benign tumors do not spread to other parts of the body. In most cases, benign tumors do not come back after they are removed. Most important, benign tumors are rarely a threat to life.
Malignant tumors are cancer.
They are generally more serious. Cancer cells can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or the lymphatic system. That is how cancer cells spread from the original (primary) tumor to form new tumors in other organs. The spread of cancer is called metastasis.
The Bile Duct
The bile duct is 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 foods.
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.
Bile Duct Cancers
Intrahepatic Bile Duct Cancers
- These cancers develop in the smaller bile duct branches inside the liver.
Perihilar Bile Duct Cancers
- These cancers 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.
Distal Bile Duct Cancers
- These bile duct cancers are found further down the bile duct, closer to the small intestine. Because these bile ducts are outside of the liver, these cancers are also known as extrahepatic bile duct cancers
More than 95% of bile duct cancers are of the adenocarcinoma
type. Adenocarcinomas are cancers of glandular cells that can develop in several organs of the body. Bile duct adenocarcinomas develop from the mucus glands that line the inside of the duct.