title: Comorbid occurrence of cholelithiasis and gastrointestinal cancer.
abstract: OBJECTIVE
  To test whether gallstone disease represents a general risk factor for gastrointestinal cancer.
  
  
  METHODS
  The comorbid occurrences of cholelithiasis or choledocholithiasis with cancers of the biliary tract, pancreas, small and large intestine were analysed in a population of 3.41 million military veterans who were discharged from VA hospitals distributed throughout the USA between 1981 and 1993. Comorbidity was calculated as the ratio between the observed and expected number of hospitalized veterans with cholelithiasis plus cancer. A 95% confidence interval was calculated based on the Poisson distribution of the observed number of patients with comorbidity.
  
  
  RESULTS
  In cholelithiasis, the ratio of comorbid occurrence with biliary cancer was 4.59 (4.06-5.31). In choledocholithiasis, the ratio of comorbid occurrence with biliary cancer was 9.31 (7.20-11.84) and with pancreatic cancer 4.34 (3.80-4.94). These ratios remained significant when the analyses were confined to cholelithiasis or choledocholithiasis documented before the first diagnosis of cancer. The ratios of the comorbid occurrences between cholelithiasis and cancers of the small or large intestine were only significant when total comorbid occurrences were analysed, but vanished in the analysis restricted to cholelithiasis or choledocholithiasis documented before the first diagnosis of cancer.
  
  
  CONCLUSIONS
  The occurrence of gallstones represents a risk factor for pancreaticobiliary cancer, but not cancers involving other parts of the gastrointestinal tract. This association appears particularly strong in patients with choledocholithiasis.
authors.affiliation: Division of Gastroenterology, Medical College of Wisconsin, USA.
authors.forename: P
authors.initials: P
authors.lastname: Bansal
authors.forename: A
authors.initials: A
authors.lastname: Sonnenberg
mesh_terms: D002769:Cholelithiasis / Q000175:diagnosis / Q000453:epidemiology*; D015897:Comorbidity / Q000639:trends; D016001:Confidence Intervals; D005770:Gastrointestinal Neoplasms / Q000175:diagnosis / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D012042:Registries; D012307:Risk Factors; D014481:United States