Background

Obesity is a worldwide pandemic. Bariatric surgery is considered the only sustained weight reduction option for obese patients. Many studies have investigated the association between obesity, bariatric surgery, and cancer with conflicting results and thus arises a need for delving deeper into these studies. Thus, we decided to use a systematic review and a meta-analysis, to explore trends in cancer prevention and their relation to bariatric surgery.

Methods

The study was conducted according to the PRISMA statement. We conducted a search using the following electronic databases through May 2020: Pubmed, Embase, and the Cochrane Library. Data analysis was performed using effect size calculation, and mean effect size using SPSS version 25.0 (IBM) and random effect models.

Results

The initial search found 11,789 potentially relevant studies. After removing duplicate articles, 5,081 articles were identified. Filtering by title and abstract resulted in 439 relevant studies. According to full-text analysis, 35 publications met the inclusion criteria, yielding a collection of randomized clinical trials, prospective cohort studies, and retrospective cohort studies. 14 had no full text available, leaving us with 21 studies eligible for data extraction.

Conclusions

According to the retrieved data from patients who underwent bariatric surgery compared to non-operated morbid obese patients, the overall cancer incidence tended to be lower in the former group, i.e., the calculated risk of cancer was reduced after bariatric surgery. Additional information collected in this study revealed the behavior of specific types of cancer in response to induced weight loss by operative means.