Esophageal adenocarcinoma after obesity surgery in a population-based cohort study.

BACKGROUND: Obesity is strongly associated with esophageal adenocarcinoma (EAC), yet it is unclear whether weight loss reduces the risk of EAC. OBJECTIVES: To test the hypothesis that the risk of EAC decreases after weight reduction achieved by obesity surgery. SETTING: 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). CONCLUSION: The risk of EAC might not decrease after obesity surgery, but larger studies with longer follow-up are needed to establish this association.