Cholecystectomy as a risk factor for colorectal cancer: a meta-analysis

Background: It has been suggested that there is an increased risk of colorectal cancer after cholecystectomy due to increased levels of secondary bile acids. Some studies suggest the risk is higher for women and for the development of right-sided tumours. Methods: A review of the literature yielded 95 relevant studies, of which 35 were suitable for a meta-analysis involving age- and sex-matched controls. Results: The pooled odds ratio for a positive association between cholecystectomy and colorectal cancer was 1.11 (95% confidence interval (CI), 1.02 to 1.21). For women the odds ratio was 1.14 (95% CI, 1.01 to 1.28), and for right-sided cancer 1.86 (95% CI, 1.31 to 2.65). Conclusions: It is possible that this small observed association may be due to a publication bias for positive results or bias within the included studies. If it is indeed a real effect, the risk to an individual is very small.