Risk of Cancer in Patients with Cholecystitis: A Nationwide Population-based Study.

Objective The objective of this study was to evaluate the risk of cancer in patients diagnosed with cholecystitis and possible interactions between cholecystitis and cholecystectomy. Methods A retrospective population-based cohort study was conducted among patients diagnosed with cholecystitis that were registered in the National Health Insurance Research Database in Taiwan between January 1, 2000 and December 31, 2010. Standardized incidence ratios (SIRs) were calculated to compare the incidence of cancer in these patients to that of the general population. Adjusted hazard ratios (HRs) were also calculated to investigate whether cholecystitis increased the risk for specific cancers. Results During a median observation period of 5.4 years, 1541 cancers occurred in 20,431 patients with cholecystitis, yielding a SIR of 1.97 (95% confidence interval [CI], 1.88-2.07). A significantly greater risk of biliary tract cancer (adjusted HR 1.72; 95% CI, 1.08-2.75) was observed after adjusting for potential risk factors. In contrast, cholecystectomy was found to attenuate the cancer risk, with the reduction of adjusted HR from 2.34 (95% CI, 1.62-3.37) to 1.28 (95% CI, 0.76-2.14). Conclusion Cholecystitis is an independent risk factor to extrahepatic biliary tract cancers, whereas cholecystectomy can attenuate the cancer risk of cholecystitis. [ABSTRACT FROM AUTHOR]