A Novel Self-expandable,Radioactive Airway Stent Loaded With ¹²⁵I Seeds:An Animal Experiment And Prospective Randomized Controlled Study

Background and Purpose:Tracheal stenting is a fast,safe and effective means of relieving malignant airway stenosis,widely used in clinical application.But the postoperative restenosis caused by neoplastic infiltration through the mesh into the lumen or granulation tissue formation above and below the mesh stents,has been affecting the long-term curative effect.To solve this problem,we have chosen the self-expandable Nitinol stents as the carrier of isotope,combined with specially designed stent treatment planning system?STENT-TPS?,to develop a new type of stent portable of ¹²⁵I seeds based on the previous research on biliary intraluminal irradiation stent and esophagus radioactive stent to support the lumen,inhibiting tumor and tracheal intima hyperplasia,prevent malignant airway restenosis after stent implantation.The purpose of this study was to investigate the feasibility and safety of a novel self-expandable stent loaded with ¹²⁵I seeds in healthy beagle dog.Materials and Methods:Under fluoroscopic guidance forty-eight self-expandable airway stents loaded with ¹²⁵I seeds were perorally placed in the main trachea of 48 healthy beagle dogs,who were randomly divided into 4 groups?Group A:0.3 mCi;Group B:0.6 mCi;Group C:0.9mCi;Control group:0 mCi?.The estimated radiation dose was calculated using the isotropic point source approximation.Radiological follow-up examinations and histopathological examinations of stented tracheal segments and their adjacent organs and tissues were performed at 2,4,8,and 16 weeks following the stenting.Results:All stents were successfully deployed in the targeted tracheal segment in the beagle dogs without procedure-related complications.Tracheal stenosis became severer gradually in all the 4 groups,which was not associated with the radioactivity of ¹²⁵I seeds?p>0.05?.The tracheal injury scores increased along with the higher dose of radioactive seeds which reached peak at 8 weeks and then turned back slightly at 16 weeks.The adjacent tissue did not show pathohistological changes under microscope,while mild and reversible ultrastructure changes were showed under electronic microscope.Conclusions:This study demonstrates that it is feasible and safe to insert this novel self-expandable airway stent loaded with ¹²⁵I seeds in healthy beagle dog.Theoretically placement of RBMS in patients with inoperable malignant airway obstruction reduces the restenosis and improves overall survival compared with placement of CBMS,which needs to be confirmed by clinical research.Background and Purpose: Airway stent placement is an immediate and effective treatment for the palliation of malignant airway obstruction.However,restenosis caused by tumor ingrowth and/or overgrowth after stenting is common.Previous study demonstrates that it is feasible and safe to insert this novel self-expandable airway stent loaded with 125 I seeds in healthy beagle dog.This study is to evaluate the safety,efficacy and superiority of a novel radioactive bare metal stent?RBMS?compared with a conventional bare metal stent?CBMS?in patients with inoperable malignant airway obstruction.Materials and methods: This prospective study was approved by the institutional ethics committee,and informed consent was obtained from each patient.Patients with malignant airway obstruction who had dyspnea were randomly assigned to receive RBMS or CBMS placement.The primary endpoint was stenosis grade,while the secondary endpoints were technical success,overall survival,and complications.A P value of less than 0.05 was considered statistically significant.Results: Between September 2013 and July 2015,66 patients with inoperable malignant airway obstruction received stent placement fluoroscopically under general anesthesia?33 in either group?.The median follow up time was 154 days?range,15-335 days?.The baseline stenosis was immediately relieved in both groups after stent placement,and the stenosis grades in the RBMS group were significantly lower than that in the CBMS group since the second month?P < 0.05?.The technical success rates of stent placement were 100% in both groups.The median survival in the RBMS group was significantly longer than that in the CBMS group?170 days vs.123 days,P <0.05?.There was no significant difference of the incidence of complications between the two groups?P > 0.05?.Conclusion: Placement of RBMS in patients with inoperable malignant airway obstruction is feasible and safe,and it significantly reduces the restenosis and improves overall survival compared with placement of CBMS.