Ratio of primary and secondary bile acids in feces - Possible marker for colorectal cancer?

PURPOSE: Increases in fecal bile acids may play a role in colorectal carcin ogenesis. The authors tested the hypothesis that high concentrations of pri mary and secondary bile acids are more common in patients with colon cancer than in patients with other gastrointestinal diseases. METHODS: In this re trospective study the secondary bile acid deoxycholic acid and the primary bile acid cholic acid were measured in the feces by enzyme-linked immunoabs orbent assay in 63 patients with colorectal cancer, 24 patients with gastri c cancer, 11 patients with biliary disorders, and 47 healthy volunteers. RE SULTS: Preoperatively, the mean deoxycholic acid values tended to be higher and the cholic acid values were significantly lower in patients with color ectal cancer than in healthy subjects. Patients with other gastrointestinal diseases had lower deoxycholic acid and cholic acid values than healthy su bjects. In healthy subjects the deoxycholic acid to cholic acid ratio range d from 0.10 to 2.86 (mean, 0.88), but in almost two-thirds, the ratio did n ot exceed 1. In contrast, the mean preoperative ratio in patients with colo rectal cancer was 2.26 (range, 0.06-7.17; P < 0.0001) and tended to be high er in patients with advanced cancer and in those with sigmoid and rectal tu mors. If 1.1 is taken as the upper Limit of normal for deoxycholic acid to cholic acid ratio, 67 percent of patients with colorectal cancer had an abn ormal value preoperatively. CONCLUSION: A high deoxycholic acid concentrati on and deoxycholic acid to cholic acid ratio may be indicators of colorecta l cancer. Further study is needed to improve sensitivity and specificity, p erhaps by combining fecal bile acid measurements with other tests, and a la rge prospective trial may be warranted to determine whether these measureme nts have value in screening for this common cancer.