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.

[An experiment of 125I radioactive pancreatic duct stents implanted in the pancreatic ducts of pigs].

OBJECTIVE: To evaluate the feasibility and safety of radioactive pancreatic duct stents implanted in the pancreatic ducts of pigs by endoscopy. METHODS: Different doses of 125I radioactive pancreatic duct stents were implanted in the pancreatic ducts of pigs by endoscopy. Blood tests were conducted before and after implantation. 14, 30 and 60 days after implantation of the radioactive stents, the pigs were euthanized in batch. All animals underwent post mortem examination to exclude intra-abdominal hemorrhage, pancreatic fistula or peritonitis. During autopsy, the liver, bile ducts, head of the pancreas, stomach and duodenum were examined for perforation, stricture or dilation and damage of the surrounding structures. RESULTS: Fourteen pigs were implanted with pancreatic duct stents by endoscopic procedures. There was no effusion, hemorrhage or necrosis in the adjacent duodenum, stomach, liver or right kidney. The normal morphological structures of the duct of Wirsung disappeared in all the treated pigs. Histopathological examination revealed that the stents were surrounded by necrotic tissue and outside fibrous tissue. During the follow-up period, the width of outside fibrous tissue gradually increased. There were no serious abnormalities noted in the blood tests after implantation. CONCLUSION: It is indicated that the radioactive stents are safe in all the different dose groups. For future clinical application, it is feasible to design a special radioactive stent for each patient according to the size, shape and position of the pancreatic tumor.

A novel approach for treatment of unresectable pancreatic cancer: design of radioactive stents and trial studies on normal pigs.

PURPOSE: Patients diagnosed with pancreatic cancer typically have a poor prognosis. The aims of these studies were to design radioactive stents and to evaluate the feasibility and safety of the stents in animals. EXPERIMENTAL DESIGN: To combine the effects of stents and brachytherapy, plastic stents with inserted iodine-125 seeds were designed and tested in 18 normal pigs. The pigs were divided into five groups on the basis of radiation dose. The estimated radiation dose at a 5-mm radial distance from the axis of the seeds was 50 Gy in group A, 100 Gy in group B, 150 Gy in group C, and 200 Gy in group D, with four pigs in each group. In the control group (n = 2), the same plastic stents with non-radioactive seeds were implanted in the pancreatic duct. RESULTS: The procedures were successfully done on 14 of 18 (78%) pigs, whereas pancreatic duct perforation occurred in four pigs (22%). The thickened wall of the dilated pancreatic duct was clearly observed in the control group. However, the normal morphologic structure of the pancreatic duct wall disappeared in the experimental groups. Histopathologic examination revealed that the stents were surrounded with necrotic tissues and lateral fibrous tissues. During the follow-up period, the width of outside fibrous tissues gradually increased. CONCLUSIONS: These results indicate that the radioactive stents are safe in all dose groups, and it is feasible to design a special radioactive stent for each patient according to the size, shape, and position of the pancreatic tumor.