Upper gastrointestinal cancer risk following bariatric surgery: meta-analysis

Obesity is a growing global epidemic, contributing to heightened risks of multiple chronic diseases, including cancer. Evidence links obesity to several malignancies, including upper gastrointestinal cancers such as oesophageal, gastric, and liver. As the need for effective weight loss intensifies, bariatric surgery is increasingly performed, and procedures have evolved, with Roux-en-Y gastric bypass and sleeve gastrectomy being the most commonly performed surgeries. Given the physiological changes after surgery, the authors conducted a systematic review and meta-analysis to examine the impact of bariatric surgery on upper gastrointestinal cancers.

Eligible studies investigating bariatric surgery and upper gastrointestinal cancer incidence were identified through MEDLINE, Embase, and citation tracking up to July 2025. Studies reporting on oesophageal, gastric, liver, pancreatic, gallbladder, biliary tract, or small intestinal cancer were included. Random-effects models were used to estimate pooled relative risks (RR) and 95% confidence intervals.

Across 20 included studies, including 1,173,113 patients undergoing bariatric surgery and 4,600,719 patients not undergoing surgery, bariatric surgery, compared with no surgery, was inversely associated with overall upper gastrointestinal cancer risk (RR 0.58, 95% confidence interval (c.i.) 0.48 to 0.71). Specifically, inverse associations were observed for oesophageal (RR 0.63, 95% c.i. 0.40 to 0.98), liver (RR 0.47, 95% c.i. 0.35 to 0.61), and gallbladder cancer (RR 0.33, 95% c.i. 0.17 to 0.65). No significant associations were found for gastric or pancreatic cancers. There were too few studies for biliary tract and small intestinal cancers to allow meta-analyses.

Bariatric surgery appears to reduce the risk of oesophageal, liver, and gallbladder cancers, supporting a role in both weight management and cancer prevention. Standardization in reporting surgical procedures is needed to clarify effects by bariatric surgery type.