Malignant biliary obstruction is a common clinical condition caused by various malignancies. Currently,biliary stent implantation guided either by fluoroscopy or endoscopy has become the most important methods for relieving malignant biliary obstruction. However, the benefit for the survival of the patients with palliation of the stent treatment is limited because no therapeutic effects on process of the tumor itself by a stent implantation. Encouraged by the success of 125I esophageal stent in esophageal carcinoma, a novel biliary stent loaded with 125I radioactive seeds has been developed in our institute. After ex vivo and in vivo evaluations for the delivery system, the investigators prospectively compare the responses to treatment with this radiation biliary stent, versus the conventional biliary SEMS in patient with malignant biliary obstruction.

Inclusion Criteria:

• Age 18 years old or older
• Biliary obstruction by any malignant process with histologically or cytologically confirmed by biopsy or previous surgical procedures
• Clinical symptoms of biliary obstruction
• Unresectable or refused to be surgically treated biliary obstruction by any malignant process
• Willing and able to comply with the study procedures and provide written informed consent to participate in the study

Exclusion Criteria:

• Suspected benign bile duct stricture
• Strictures that can not be dilated enough to pass the delivery system
• Perforation of any duct within the biliary tree
• Presence metallic biliary stent or bile duct surgery
• Patients for whom PTC procedures are contraindicated
• Patients with active hepatitis or intrahepatic metastases that extensively involves both lobes of the liver
• Noncooperation or no authorization and signature