The exact cause of bile duct cancer is unknown, according to Healthline, but scientists implicate mutations in the bile duct cells' DNA. Bile duct cancer is a type of liver cancer that starts in the bile duct cells. The bile duct is a tube that extends from the liver to the small intestines.
There are three types of bile duct cancer, as outlined by Healthine.com. Each is classified by the location in which the cancer appears. The first group, called perinilar bile duct cancer, is the most common and occurs where the bile ducts merge and exit the liver. The second group is distal bile duct cancer, which occurs in the last part of the duct system that passes through the pancreas and ends in the duodenum. The third type is intrahepatic bile duct cancer, which occurs within the liver itself. The intrahepatic type comprises one in 10 cases of bile duct cancer.
Regardless of the type, bile duct cancer obstructs the flow of bile from the liver into the small intestines. Therefore, Healthline.com includes jaundice, which is a yellowing of the eyes, as the main symptom of bile duct cancer. Additional symptoms include weight loss, fatigue and weakness, decreased appetite, abdominal pain, itching and clay-colored stools.