Drug-eluting stent in malignant biliary obstruction

In unresectable malignant bile duct obstruction, endoscopic stent insertion is the treatment of choice. However, the current stent allows only mechanical palliation of the obstruction, and has no anti-tumor effect. Currently, in the vascular field, the drug-eluting stent (DES) is very highly favored. The requirements for a DES in a non-vascular tract, such as the bile duct, are far different from those of a DES to be used in the vascular tract. The non-vascular DES must suppress tumor proliferation as well as mucosal hyperplasia. For example, the non-vascular stent might be covered with a membrane that gradually releases a chemo-agent. We do not have much experience with DES in the bile duct. Nonetheless, we are continuously testing many anti-tumor agents in animal and human studies. We expect and hope DES will work effectively for tumor cells in diverse ways and, more importantly, will prolong stent patency and the patients' survival periods. But considerable investigation and a clinical study of DES will be required to achieve these goals.