Effects of Bariatric Surgery on Cancer Risk: Evidence from Meta-analysis

Introduction Weight loss after bariatric surgery yields important health benefits. A multitude of observational studies have investigated the association of bariatric surgery for severe obesity with the risk of cancer. However, the results were debatable. The aim of the present study was to estimate the effect of bariatric surgery on overall cancer risk. Methods A systematic literature search was performed to identify studies evaluating the association of bariatric surgery for severe obesity with the risk of cancer. Meta-analysis was performed to calculate combined prevalence. Results Twenty-one cohort studies with 304,516 patients with obesity having under gone bariatric surgery and 8,492,408 patients with obesity as controls were included. Meta-analysis found decreased cancer risk to be associated with bariatric surgery (OR = 0.56, 95% CI = 0.48–0.66), both for the incidence of cancer (OR = 0.56, 95% CI = 0.46–0.68) and mortality of cancer (OR = 0.56, 95% CI = 0.41–0.75). In subgroup analysis, bariatric surgery was significantly associated with decreased breast cancer risk and endometrial cancer risk, but not associated with other cancer risk. Conclusions Our meta-analysis indicated that bariatric surgery for severe obesity was associated with decreased cancer risk, both for cancer incidence and mortality. Moreover, further studies estimating the functional effect and side effects may eventually provide a better, comprehensive understanding.