Decreased Risk of Esophageal Adenocarcinoma after Gastric Bypass Surgery in a Cohort Study from Three Nordic Countries

To test the hypothesis that bariatric surgery decreases the risk of esophageal and cardia adenocarcinoma. Obesity is strongly associated with esophageal adenocarcinoma and moderately with cardia adenocarcinoma, but whether weight loss prevents these tumors is unknown. This population-based cohort study included patients with an obesity diagnosis in Sweden, Finland, or Denmark. Participants were divided into a bariatric surgery group and a non-operated group. The incidence of ECA was first compared with the corresponding background population by calculating standard incidence ratios (SIR) with 95% confidence intervals (CI). Second, the bariatric surgery group and the non-operated group were compared using multivariable Cox regression, providing hazard ratios (HR) with 95% CI, adjusted for sex, age, comorbidity, calendar year, and country. Among 748,932 participants with an obesity diagnosis, 91,731 underwent bariatric surgery, predominantly gastric bypass (n=70,176; 76.5%). The SIRs of ECA decreased over time following gastric bypass, from SIR=2.2 (95% CI 0.9-4.3) after 2-5 years to SIR=0.6 (95% CI