A novel approach for treatment of unresectable extrahepatic bile duct carcinoma: design of radioactive stents and an experimental trial in healthy pigs

Background Patients diagnosed with extrahepatic bile duct carcinoma (EBDC) have a poor prognosis. Objective The purpose of these studies was to design radioactive stents for EBDC and to evaluate the feasibility and safety of the stents in healthy pigs. Design Plastic stents with inserted iodine-125 seeds were designed and tested in 11 healthy pigs. The pigs were divided into 4 groups on the basis of radiation doses. Interventions The stents with estimated radiation dose at a 5-mm radial distance from the axis of the seeds of 30 Gy, 60 Gy, and 90 Gy were implanted in the common bile duct (CBD) in groups A, B, and C (n = 3 in each group), with the control group (n = 2) being implanted with the stents containing nonradioactive seeds. Main Outcome Measurements Histologic evaluation was performed under a light microscope. Results The procedures were successfully performed on all pigs. Severe hyperplasia of the mucosa was seen in the control group. In the experimental groups, obvious mucosal necrosis near the radioactive seeds was observed but without perforation of the CBD wall. In lower-dose groups (30 Gy), mild hyperplasia of mucosal glands with fibrosis under the necrosis layer was seen. However, after the increase of the dose, mucosal glands were disappearing without a visible mucosal layer. Conclusions The radioactive stents are safe at each dose in healthy pigs. Moreover, our observations indicate the feasibility to design specific radioactive stents according to the size, shape, and position of EBDC in future clinical applications.