Role of bile acids and metabolic activity of colonic bacteria in increased risk of colon cancer after cholecystectomy.

Since the metabolic activity of the colonic flora plays a definite role in colon cancer and an increased incidence of this disease is reported after cholecystectomy, we studied the metabolic activity of the colonic flora in a group of postcholecystectomy patients and matched controls by measuring, as representative end products of the bacterial metabolism, their fecal bile acids (BA), fecal 3-methylindole (SK) and indole (IN), and respiratory methane and hydrogen. Patients had significantly higher SK and lower IN, and, among BA, higher lithocholic (LCA) and chenodeoxycholic acid concentrations and LCA/deoxycholic acid ratio in the stools than controls. Similar differences from controls were reported for colon cancer. Comparable bacterial metabolic activities are thus operative in the large bowel of postcholecystectomized and colon cancer patients. This supports the biological plausibility of the association of cholecystectomy and colon cancer.