Cholecystectomy and the risk of colon cancer

Objective: The relationship between cholecystectomy and the occurrence of subsequent colon cancer has been controversial. Using data collected as part of an incident case-control study of colon cancer conducted in northern California, Minnesota, and Utah, we evaluated this association. Methods: Participants were between 30 and 79 yr of age and had a first primary colon cancer diagnosed between October 1, 1991 and September 30, 1994. Analyses were adjusted for age, gender, family history of colorectal cancer, body mass index, dietary energy and fiber intake, use of aspirin or nonsteroidal antiinflammatory drugs, and long-term leisure-time vigorous physical activity. Results: A weak positive association between cholecystectomy and proximal colon cancer (odds ratio [OR] and 95% confidence interval [CI] 1.3 [1.0–1.6]) was observed. This was counterbalanced by a weak, nonsignificant negative association (OR 0.8, 95% CI 0.6–1.1) with distal colon cancer leading to no overall association (OR 1.0, 95% CI 0.9–1.2). The association between colon cancer and cholecystectomy did not differ by gender or race, but it did differ by study area, with most of the increased association being attributed to the Minnesota population. The elevated risk of proximal colon cancer increased after cholecystectomy but disappeared after 14 years. Conclusions: Our results suggest that cholecystectomy or the underlying gallstone disease that prompts it may be related weakly to the risk of subsequent proximal colon cancer. However, the association may differ by geographic area of the country, and may be artifactual at least in part.