Effects of a 3-mo consumption of short-chain fructo-oligosaccharides on parameters of colorectal carcinogenesis in patients with or without small or large colorectal adenomas.

Intervention studies of colorectal adenoma recurrence have demonstrated the need for surrogate markers of the cancer risk. Short-chain fructo-oligosaccharides (sc-FOS) have protective actions on colon carcinogenesis in animal models. We investigated differences in biological markers between adenoma and adenoma-free subjects, before and after 3 mo of daily intake of 10 g sc-FOS, within a multicenter study. After a full colonoscopy, 3 groups were studied at baseline and after 3 mo: 26 subjects with small colorectal adenoma(s), 18 with large adenoma(s), and 30 with no adenoma. At baseline, the mean fecal butyrate concentration was significantly lower in the adenoma groups than in the adenoma-free group (12.01 +/- 5.08 vs. 17.28 +/- 7.34 mmol/g dry weight) but was significantly increased in that group after 3-mo ingestion of sc-FOS (15.7 +/- 8.0 mmol/g; P = 0.02). In subjects without adenoma, sc-FOS ingestion was associated with a decrease in fecal lithocholic acid (P = 0.02) and an increase in cholic acid (P = 0.02), chenodeoxycholic acid (P = 0.04), total primary bile acids (P = 0.03), and ursodeoxycholic acid (P = 0.05). Fecal pH, blood parameters, and crypt cell proliferation were not significantly modified by sc-FOS ingestion in either group. In subjects with and without adenoma, sc-FOS affects some aspects of the colonic environment, which may be involved in prevention of colorectal neoplasia.

Fecal primary bile acids and serum cholesterol are associated with colorectal adenomas.

In order to identify biomarkers of colorectal tumors, 20 subjects with colorectal adenomas were compared with 20 controls as regards fecal parameters (pH, short-chain fatty acids, bile acids, and sterols), blood parameters (bile acids, cholesterol, triglycerides, glycemia and insulinemia), and rectal cell proliferation. Variables were compared by unconditional logistic regression, controlling for gender. There were significant and positive associations between risk of adenoma and total fecal primary bile acids and serum cholesterol, with odds ratios for the third versus first tertile = 9.4 (P for trend = 0.03) and 8.6 (P for trend = 0.04), respectively. There was a trend towards an increased triglycerides level in adenoma subjects compared with controls (P = 0.08). These three parameters correlated with cell proliferation, although cell proliferation itself was not significantly associated with adenomas. In conclusion, these results suggest that fecal primary bile acids and serum cholesterol are markers of early events of colorectal carcinogenesis.