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

Background: Obesity is strongly associated with esophageal adenocarcinoma (EAC), yet whether weight loss reduces the risk of EAC is unclear. Objectives: To test the hypothesis that the risk of EAC decreases following 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 1980-2012. The incidence of EAC following obesity surgery was compared to 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 was also compared with the risk in non-operated obese individuals by means of multivariable Cox regression, providing hazard ratios (HRs) with 95% CIs, adjusted for potential confounders. Results: Among 34,437 study participants undergoing obesity surgery and 239,775 person- 15" years of follow-up, 8 cases of EAC occurred (SIR 1.6, 95% CI 0.7-3.2). No clear trend of decreased SIRs was seen in relation to increased follow-up time after surgery. The SIR of EACs (n=53) among 123,695 non-operated obese individuals (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 showed no difference in risk of EAC between operated and non-operated participants (adjusted HR=0.9, 95% CI 0.4-1.9). Conclusions: The risk of EAC might not decrease following obesity surgery, but even larger studies with longer follow-up are needed to establish this association.The Swedish Research Council (SIMSAM), the Swedish Cancer Society, and the Nordic Cancer Union.Accepte