Role of bariatric surgery in reducing the risk of colorectal cancer: a meta-analysis.

Abstract

Obesity increases the risk of multiple co-morbidities such as type 2 diabetes, cardiovascular disease and most cancers, including colorectal cancer. Currently, the literature presents conflicting results regarding the protective effects of bariatric surgery on the incidence of colorectal cancer. This meta-analysis was conducted to investigate the effect of bariatric surgery on the risk of developing colorectal cancer in obese individuals. Ovid Embase, Ovid MEDLINE, Cochrane CENTRAL and Web of Science were searched for relevant articles. Articles published by the end of December 2018 were retrieved; data were extracted according to evidence-based PICO (population, intervention, control, outcome) model and analysed using a random-effects model to estimate the pooled relative risk (RR) and its 95 per cent confidence interval. The heterogeneity of studies was tested and quantified using Cochran's Q and I2 statistics. Meta-regression was used to investigate the association of year of study, region, mean length of follow-up and sample size with RR. Seven articles, involving a total of 1 213 727 patients, were included in the meta-analysis. The pooled estimate of the RR was 0·64 (95 per cent c.i. 0·42 to 0·98). The test of asymmetry found no significant publication bias. Meta-regression showed that sample size was a statistically significant factor (P = 0·037), but year of publication, region and mean duration of follow-up were not significant. Patients who underwent bariatric surgery had a greater than 35 per cent reduction in the risk of developing colorectal cancer compared with obese individuals who had no surgery.