Simultaneous Assay of Fecal Short-Chain Fatty and Bile Acids and Ratio of Total Bile Acids to Butyrate in Colon Cancer

We simultaneously quantified fecal bile acids (BAs) and short-chain fatty acids (SCFAs) florescence labeled with 9chloromethylanthracene using high-performance liquid chromatography-fluorescence (HPLC-FL) and developed an inexpensive and highly accurate method for determining the ratio of BAs and SCFAs in colorectal cancer patients and healthy controls. Samples were extracted with hexane/ether, and extractants were measured using HPLC-FL. The healthy subject group included 17 men and 21 women, whereas the colorectal cancer group included patients with cancer in the rectum (3 men, 2 women), sigmoid colon (3 men, 2 women), and ascending colon (2 men, 3 women). The contribution rate of determination for calibration curves was >0.99, and the additional recovery rate was 67.2%–107% for the simultaneous quantification of fecal BAs and SCFAs using HPLC-FL. Intra-day and inter-day variations in the control feces ranged 2.4%–5.1% and 3.1%–9.2%, respectively. The proportion of primary BAs to total BAs was higher in the colorectal cancer group (87.3%) than in the healthy subject group (67.9%). A significant difference was observed in the ratio of BAs to butyric acid between healthy subject and colorectal cancer groups. BA levels were higher in the colorectal cancer group. Thus, the ratio of total BAs to butyric acid may be a better predictor of colon cancer than BAs or SCFAs alone.