Modern gastrointestinal endoscopic techniques for biliary tract cancers
Biliary tract cancers, specifically cholangiocarcinomas (CCAs), arise from the epithelial cells of the biliary tree. They can be divided into three groups based on their location: intra-hepatic, peri-hilar or distal extra-hepatic CCAs. Traditionally, the main role of endoscopy in the management of biliary tract cancers was diagnosis and biliary decompression. For diagnosis, endoscopic retrograde cholangiopancreatography (ERCP) can be used to obtain either brushings or intra-ductal biopsies however both techniques have poor sensitivity. The introduction of cholangioscopy has allowed endoscopists to perform both targeted biopsies and also obtain a visual diagnosis. Similarly, with the spread of endoscopic ultrasound (EUS), the ability to obtain tissue by fine-needle aspiration is another avenue available, but concerns regarding tumor seeding still persist. For biliary decompression, with the advent of neo-adjuvant therapy, the role of early decompression is growing. Nevertheless, it is still not clear whether endoscopic decompression is superior to percutaneous decompression, especially in advanced hilar tumors. When possible, at least 50% of viable liver should be drained, and that will determine whether unilateral or bilateral stents are required. Additionally, there is growing evidence on the benefits of metal stents over plastic stents, but care should be taken as metal stents are generally permanent. Finally, although not widely available or adopted, with the growing use of radiofrequency ablation and the introduction of drug-eluting metal stents, the near-future might allow newer techniques to treat the disease itself.