Association between fecal bile acids and colorectal cancer: a meta-analysis of observational studies

Abstract

Purpose: To provide a systematic review with meta-analysis for addressing the relationship between fecal bile acids (FBAs) and colorectal cancer.

Materials and methods: Electronic databases were searched for all observational studies that examined the relationship between FBAs and colorectal cancer or adenoma, and calculated weighted mean difference (WMD) and 95% confidence interval (CI). Publication bias was assessed with funnel plot.

Results: Twenty case-control or cohort studies were identified. All studies were pooled to assess the relationship between total FBAs and cancer/adenoma of the large bowel, however, no association was seen (WMD 0.61mg/g freeze-dried feces; 95% CI: -0.35-1.57). Significantly increased concentration of chenodeoxycholic acid (CDCA) was seen while pooling to assess the relationship between CDCA and cancer/adenoma of the large bowel (WMD 0.13 mg/g freeze-dried feces; 95% CI: 0.01-0.25), especially for colorectal cancer (WMD 0.28mg/g freeze-dried feces; 95% CI: 0.10-0.46). However, no significant differences in deoxycholic acid (DCA), lithocholic acid (LCA), and primary and secondary bile acids, were seen between patients with cancer and patients with matched controls regardless of fixed and random effects models.

Conclusion: CDCA might play a role in the etiology of colorectal cancer.

Fig. 1

Trial flow for selection relating studies.

Fig. 2

Summary estimates of the WMD for total bile acids concentration in individuals with colorectal cancer/adenoma vs. matched controls under random effects model. CI, confidence interval; WMD, weighted mean difference.

Fig. 3

Summary estimates of the WMD for CDCA concentration in individuals with colorectal cancer/adenoma vs. matched controls under fixed effects model. CI, confidence interval; WMD, weighted mean difference; CDCA, chenodeoxycholic acid.

Fig. 4

Summary estimates of the WMD for DCA concentration in individuals with colorectal cancer/adenoma vs. matched controls under random effects model. CI, confidence interval; WMD, weighted mean difference; DCA, deoxycholic acid.

Fig. 5

Summary estimates of the WMD for LCA concentration in individuals with colorectal cancer/adenoma vs. matched controls under random effects model. CI, confidence interval; WMD, weighted mean difference; LCA, lithocholic acid.

Fig. 6

Summary estimates of the WMD for primary bile acids concentration in individuals with colorectal cancer/adenoma vs. matched controls under fixed effects model. CI, confidence interval; WMD, weighted mean difference.

Fig. 7

Summary estimates of the WMD for secondary bile acids concentration in individuals with colorectal cancer/adenoma vs. matched controls under fixed effects model. CI, confidence interval; WMD, weighted mean difference.

Fig. 8

Begg's funnel plot with pseudo 95% confidence limits showing WMD in total bile acids by standard error of WMD. WMD, weighted mean difference.