title: Polytetrafluoroethylene-covered retrievable expandable nitinol stents for malignant esophageal obstructions: factors influencing the outcome of 270 patients.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the clinical effectiveness of polytetrafluoroethylene (PTFE)-covered retrievable expandable nitinol stents in patients with malignant esophageal strictures and to identify prognostic factors associated with clinical outcomes.
  
  
  METHODS
  From 2001 to 2010, 320 PTFE-covered stents were placed in 270 patients. Technical and clinical success, complications, survival, and stent patency were measures of clinical effectiveness. The relationships among complications and age, sex, stricture location, stricture length, chemotherapy alone, chemoradiotherapy, and malignancy source were examined. Independent prognostic factors of overall survival and stent patency were identified.
  
  
  RESULTS
  Stent placement and removal were technically successful and tolerated without procedural complications, and 98% of patients achieved clinical success. The complication rate was 30%. Two removed stents exhibited covering membrane separation. Chemotherapy was associated with increased stent migration (p = 0.002). Stricture location and chemoradiotherapy were associated with esophagorespiratory fistula development (p = 0.033 and p < 0.001, respectively). Median and mean survival periods were 114 days (95% CI, 102-126 days) and 166 days (138-193 days). Chemotherapy and chemoradiotherapy were independent prognostic factors for survival (p = 0.050 and p = 0.032, respectively). The median and mean stent patency periods were 60 days (41-79 days) and 90 days (71-108 days). Chemoradiotherapy was the only independent prognostic factor for stent patency (p = 0.012).
  
  
  CONCLUSIONS
  The PTFE-covered stents were clinically effective. Membrane degradation was not evident, although 0.7% of the patients experienced covering membrane separation. Chemotherapy was associated with increased migration and prolonged survival. Chemoradiotherapy was associated with increased esophagorespiratory fistula formation and decreased stent patency.
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul, 138-736, Republic of Korea.
authors.forename: Jung-Hoon
authors.initials: JH
authors.lastname: Park
authors.forename: Ho-Young
authors.initials: HY
authors.lastname: Song
authors.forename: Jin Hyoung
authors.initials: JH
authors.lastname: Kim
authors.forename: Hwoon-Yong
authors.initials: HY
authors.lastname: Jung
authors.forename: Jong-Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Sung-Bae
authors.initials: SB
authors.lastname: Kim
authors.forename: Heuiran
authors.initials: H
authors.lastname: Lee
mesh_terms: D000497:Alloys; D020099:Coated Materials, Biocompatible; D003131:Combined Modality Therapy; D020878:Device Removal; D004938:Esophageal Neoplasms / Q000473:pathology / Q000628:therapy*; D004940:Esophageal Stenosis / Q000473:pathology / Q000628:therapy*; D005260:Female; D005471:Fluoroscopy; D005548:Foreign-Body Migration / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011138:Polytetrafluoroethylene; D011379:Prognosis; D016016:Proportional Hazards Models; D015641:Radiography, Interventional; D012189:Retrospective Studies; D012307:Risk Factors; D015607:Stents / Q000009:adverse effects; D015996:Survival Rate; D016896:Treatment Outcome
chemical_list: D000497:Alloys; D020099:Coated Materials, Biocompatible; C013616:nitinol; D011138:Polytetrafluoroethylene