Cholecystectomy, gallstones, tonsillectomy, and pancreatic cancer risk: a population-based case-control study in minnesota

Background: Associations between medical conditions and pancreatic cancer risk are controversial and are thus evaluated in a study conducted during 1994-1998 in Minnesota. Methods: Cases (n=215) were ascertained from hospitals in the metropolitan area of the Twin Cities and the Mayo Clinic. Controls (n=676) were randomly selected from the general population and frequency matched to cases by age and sex. The history of medical conditions was gathered with a questionnaire during in-person interviews. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using unconditional logistic regression. Results: After adjustment for confounders, subjects who had cholecystectomy or gallstones experienced a significantly higher risk of pancreatic cancer than those who did not (OR ( 95% CI): 2.11 (1.32-3.35) for cholecystectomy and 1.97 (1.23-3.12) for gallstones), whereas opposite results were observed for tonsillectomy (0.67 (0.48-0.94)). Increased risk associated with cholecystectomy was the greatest when it occurred <= 2 years before the cancer diagnosis (5.93 (2.36-15.7)) but remained statistically significant when that interval was >= 20 years (2.27 (1.16-4.32)). Conclusions: Cholecystectomy, gallstones, and tonsillectomy were associated with an altered risk of pancreatic cancer. Our study suggests that cholecystectomy increased risk but reverse causality may partially account for high risk associated with recent cholecystectomy.