A comparative analysis of fecal bile acid profiles in patients with ulcerative colitis and colorectal cancer

Abstract

Ulcerative colitis (UC) is a chronic inflammatory disease of the colon in which mucosal inflammation, dysbiosis, and colorectal cancer (CRC) risk are closely linked. Because intestinal bacteria convert primary bile acids into secondary bile acids, fecal bile acid composition may help describe metabolic differences between inflammatory and malignant colorectal disease. Therefore, the aim of this study was to compare fecal bile acid profiles in patients with UC and CRC, with colonoscopy-negative controls included as an additional comparator. This cross-sectional analytical study enrolled 100 participants: 40 with UC, 40 with CRC, and 20 colonoscopy-negative controls without macroscopic colorectal abnormalities. Fecal cholic acid (CA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), and lithocholic acid (LCA) were measured by liquid chromatography-mass spectrometry (LC-MS) and expressed in nmol/g. Data were summarized as median and interquartile range. UC and CRC were compared using the Mann-Whitney test, while three-group analysis used the Kruskal-Wallis test followed by Bonferroni-corrected post-hoc Mann-Whitney tests. Fecal bile acid profiles differed significantly between UC and CRC. UC showed higher levels of CA (p<0.001), CDCA (p=0.001), and total primary bile acid (p<0.001). Conversely, CRC showed higher levels of DCA, LCA, total secondary bile acids, total bile acids, and secondary-to-primary bile acid ratios (all p<0.001). In the three-group analysis, the overall significant differences (all p≤0.002) were driven mainly by the CRC group. No statistically significant differences were detected between UC and colonoscopy-negative controls for any measured parameter, although this finding should not be interpreted as evidence of equivalent or normal fecal bile acid profiles. In conclusion, these distinct metabolic signatures suggest that fecal bile acids have potential as non-invasive biomarkers to differentiate colorectal malignancy from chronic inflammation.