Introduction: 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. Material and methods: 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. Conclusion: 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.
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