title: Esophageal adenocarcinoma after obesity surgery in a population-based cohort study.
abstract: BACKGROUND
  Obesity is strongly associated with esophageal adenocarcinoma (EAC), yet it is unclear whether weight loss reduces the risk of EAC.
  
  
  OBJECTIVE
  To test the hypothesis that the risk of EAC decreases after weight reduction achieved by obesity surgery.
  
  
  METHODS
  Nationwide register-based cohort study.
  
  
  METHODS
  This study included a majority of individuals who underwent obesity surgery in Sweden in 1980 to 2012. The incidence of EAC after obesity surgery was compared with the incidence in the corresponding background population of Sweden by means of calculation of standardized incidence ratios (SIRs) with 95% confidence intervals (CIs). The risk of EAC after obesity surgery also was compared with the risk in obese individuals who did not undergo obesity surgery by means of multivariable Cox regression, providing hazard ratios with 95% CIs, adjusted for potential confounders.
  
  
  RESULTS
  Among 34,437 study participants undergoing obesity surgery and 239,775 person-years of follow-up, 8 cases of EAC occurred (SIR 1.6; 95% CI .7-3.2). No clear trend of decreased SIRs was observed in relation to increased follow-up time after surgery. The SIR of EACs (n = 53) among 123,695 obese individuals who did not undergo obesity surgery (673,238 person-years) was increased to a similar extent as in the obesity surgery cohort (SIR = 1.9, 95% CI 1.4-2.5). Cox regression demonstrated no difference in risk of EAC between participants who underwent obesity surgery and those who did not (adjusted hazard ratio = .9, 95% CI .4-1.9).
  
  
  CONCLUSIONS
  The risk of EAC might not decrease after obesity surgery, but larger studies with longer follow-up are needed to establish this association.
authors.affiliation: Upper Gastrointestinal Surgery, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden. Electronic address: John.Maret.Ouda@ki.se.
authors.forename: John
authors.initials: J
authors.lastname: Maret-Ouda
authors.affiliation: Upper Gastrointestinal Surgery, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Tao
authors.affiliation: Upper Gastrointestinal Surgery, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Mattsson
authors.affiliation: Upper Gastrointestinal Surgery, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Nele
authors.initials: N
authors.lastname: Brusselaers
authors.affiliation: Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, Texas.
authors.forename: Hashem B
authors.initials: HB
authors.lastname: El-Serag
authors.affiliation: Upper Gastrointestinal Surgery, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden; Section of Gastrointestinal Cancer, Division of Cancer Studies, King's College, London, UK.
authors.forename: Jesper
authors.initials: J
authors.lastname: Lagergren
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology*; D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D050110:Bariatric Surgery / Q000706:statistics & numerical data*; D015331:Cohort Studies; D004938:Esophageal Neoplasms / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology* / Q000601:surgery; D011183:Postoperative Complications / Q000453:epidemiology; D012042:Registries; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult
keywords: Bariatric surgery; Cancer; Neoplasm; Obesity; Weight loss