Association between metabolic and bariatric surgery and malignancy: a systematic review, meta-analysis, trends, and conclusions.

Background: Conflicting studies have investigated the association between obesity, metabolic and bariatric surgery (MBS), and cancer.

Objectives: Our study aimed at elucidating the trends in cancer incidence that are related to obesity and weight loss managed through MBSs, like Colo-rectal, breast, uterine, and esophageal cancer.

Setting: We conducted a search using PubMed, Embase, and the Cochrane Library electronic databases through May 2020.

Methods: A systematic review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement.

Results: MBS procedures surveyed included sleeve gastrectomy, gastric band, gastric bypass, gastric balloon, and banded gastroplasty/silastic ring gastroplasty. The initial search found 11,789 potential studies. After data extraction and filtering, 21 were included in the final analysis. Overall, the calculated risk of cancer was reduced after MBS in comparison to the patients suffering from obesity who were treated nonoperatively (mean effect size of -.33). It was also found as a protective factor against colorectal cancer (mean E.S. -.28), uterine cancer (mean E.S. -.42), breast cancer (mean E.S. -.37), and esophageal cancer (mean E.S. -.23). Other cancers, such as liver, pancreatic, and skin, did not show a significant change even though a trend was seen.

Conclusions: According to the data retrieved from patients who underwent MBS compared to nonoperated patients suffering from obesity, the overall risk for malignancy was lower in the MBS group. Additional information collected in this study revealed the behavior of specific types of cancer in response to induced weight loss by operative means. The benefit of surgery in patients suffering from obesity is not restricted to the improvement of obesity morbidity alone.