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

BackgroundPatients diagnosed with extrahepatic bile duct carcinoma (EBDC) have a poor prognosis.ObjectiveThe purpose of these studies was to design radioactive stents for EBDC and to evaluate the feasibility and safety of the stents in healthy pigs.DesignPlastic 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.InterventionsThe 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 MeasurementsHistologic evaluation was performed under a light microscope.ResultsThe 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.ConclusionsThe 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.