What is cholangiocarcinoma?
Cholangiocarcinoma is a malignancy originating from the epithelium of the biliary ducts. It may originate anywhere along the biliary tree and is often slow-growing. These are poorly vascularized tumors that spread along the lymphatic system.
How common is cholangiocarcinoma?
The worldwide incidence of cholangiocarcinoma varies geographically. In the United States, the incidence is less than 1 percent, and often occurs in elderly individuals with chronic liver disease. In Thailand, cholangiocarcinoma is associated with liver flukes (Clonorchis sinensis and Opisthorchis viverrini).
What conditions cause cholangiocarcinoma?
A variety of risk factors have been associated with cholangiocarcinoma. These include primary sclerosing cholangitis (PSC), liver flukes, perhaps intrahepatic gallstones, congenital cystic dilatations of the biliary tree (Caroli disease, also known as Type V choledochocele) and choledochal cysts. In addition, Thorotrast, a radiocontrast used until the 1950s, has been reported to be associated with the development of cholangiocarcinoma.
What laboratory tests should be sent off if cholangiocarcinoma is suspected?
Given the low incidence of cholangiocarcinoma in the United States, physicians need to suspect cholangiocarcinoma in any at-risk individual, often with chronic liver disease. Routine liver function tests should be ordered, often revealing a nonspecific cholestatic pattern. Certain tumor markers including CEA, CA 19-9, and AFP should be ordered, however, these are positive in less than 40 percent of cases.
What imaging modalities are available to help diagnose cholangiocarcinoma?
A transabdominal ultrasound is useful, but usually cannot visualize the tumor itself. It may, however, visualize the tumor’s effects on bile duct obstruction (i.e., bile duct dilation). Note that in peripheral and hilar cholangiocarcinoma, distal bile ducts will not be dilated. Rarely, metastatic liver lesions may be visualized. Another common imaging modality is CT scan, where the tumor usually appears hypovascular and hypodense or isodense to the hepatic parenchyma. This is useful to differentiate cholangiocarcinoma from the more hypervascular hepatocellular carcinoma. Also, lymphadenopathy can be easily assessed. MRI is slightly superior to CT scan for tumor visualization. It can be combined with a magnetic resonance cholangiopancreatography (MRCP) to safely evaluate ductal architecture without exposing patients to radiation. Unfortunately, therapy requires endoscopic retrograde cholangiopancreatography (ERCP). Endoscopic ultrasound (EUS) is very useful for imaging parts of the hepatobiliary tree. The precision of EUS in diagnosing cholangiocarcinoma remains to be completely elucidated.
How is cholangiocarcinoma treated?
Surgery is the treatment of choice in patients with resectable cholangiocarcinoma. The actual type of resection performed depends on the location of the tumor. The mortality rates and tumor resectability depend on tumor location and presence of metastases at the time of surgical exploration. Distal tumors exhibit the highest resection rates.
How is unresectable cholangiocarcinoma managed?
Currently, there are no effective chemotherapeutic or radiotherapeutic options available that have shown significant improvement in the clinical outcome of patients with cholangiocarcinoma. Palliative management (stenting of the biliary tree) relieves jaundice and the risk of cholangitis. Stenting can be accomplished by ERCP or by the percutaneous transhepatic approach.