Extrahepatic biliary cancer: New staging classification

Tumor staging defines the point in the natural history of the malignancy when the diagnosis is made. The most common staging system for cancer is the tumor, node, metastases classification. Staging of cancers provides useful parameters in the determination of the extent of disease and prognosis. Cholangiocarcinoma are rare and refers to cancers that arise from the biliary epithelium. These tumors can occur anywhere along the biliary tree. These tumors have been previously divided into extrahepatic and intrahepatic lesions. Until recently the extrahepatic bile duct tumors have been considered as a single entity per American Joint Commission on Cancer (AJCC) staging classification. The most recent changes to the AJCC classification of bile duct cancers divide the tumors into two major categories: proximal and distal tumors. This practical classification is based on anatomy and surgical management. High quality cross-sectional computed tomography (CT) and/or magnetic resonance (MR) imaging of the abdomen are essential information to accurately stage this tumors. Imaging plays an important role in diagnosis, localization, staging and optimal management of cholangiocarcinoma. For example, it helps to localize the tumor to either perihilar or distal bile duct, both of which have different management. Further, it helps to accurately stage the disease and identify the presence of significant nodal and distant metastasis, which may preclude surgery. Also, it helps to identify the extent of local invasion, which has a major impact on the management. For example, extensive involvement of hepatic duct reaching up to second-order biliary radicals or major vascular encasement of portal vein or hepatic arteries precludes curative surgery and patient may be managed by palliative therapy. Further, imaging helps to identify any anatomical variations in the hepatic arterial or venous circulation and biliary ductal system, which is vital information for surgical planning. This review presents relevant clinical presentation and imaging acquisition and presentation for the accurate staging classification of bile duct tumors based on the new AJCC criteria. This will be performed with the assistance of anatomical diagrams and representative CT and MR images. The image interpretation must include all relevant imaging information for optimum staging. Detailed recommendations on the items required on the radiology report will be presented.