The possible carcinogenic effect of cholecystectomy. No postoperative increase in the proportion of secondary bile acids.

In consecutive patients with gallstones in well-functioning gallbladders, duodenal bile was sampled before and 2 to 3 months after cholecystectomy. The preoperative and postoperative bile acid patterns were compared. Cholecystectomy resulted in a significant shift from cholic- to chenodeoxycholic acid. This shift could help to explain the low incidence of recurrent common duct stones. The percentage of secondary bile acids showed very little change. An increase of the mean preoperative value of 3.9 percentage points or more was improbable (P = 0.025). This finding refutes the hypothesis that cholecystectomy could lead to colonic cancer via an increase in the proportion of secondary bile acids. An alternative hypothesis is proposed for the reported high incidence of previous cholecystectomy in colonic cancer. Both gallstones and cancer of the colon may be associated with high levels of secondary bile acids.