title: Intestinal cancer after cholecystectomy: is bile involved in carcinogenesis?
abstract: OBJECTIVE
  Results concerning an association between cholecystectomy and right-sided colon cancer are inconsistent. Little is known about the relation between cholecystectomy and small bowel cancer. Therefore, we evaluated cholecystectomy and risk of bowel cancer.
  
  
  METHODS
  Cholecystectomized patients, identified through the Swedish Inpatient Register, from 1965 through 1997, were followed up for subsequent cancer. The standardized incidence ratio (SIR) estimated relative risk.
  
  
  RESULTS
  In total, 278,460 cholecystectomized patients, contributing 3,519,682 person-years, were followed up for a maximum of 33 years after surgery. Cholecystectomized patients had an increased risk of proximal intestinal adenocarcinoma, which gradually declined with increasing distance from the common bile duct. The risk was significantly increased for adenocarcinoma (SIR, 1.77; 95% confidence interval [CI], 1.37-2.24) and carcinoids of the small bowel (SIR, 1.71; 95% CI, 1.39-2.08), and right-sided colon cancer (SIR, 1.16; 95% CI, 1.08-1.24). No association was found with more distal bowel cancer. The gradient was further pronounced when surgery of the common bile duct was included. The associations remained increased up to 33 years after cholecystectomy. No differences between sexes were found.
  
  
  CONCLUSIONS
  Cholecystectomy increases the risk of intestinal cancer, a risk that declines with increasing distance from the common bile duct. Changes in the intestinal exposure to bile might be the underlying biological mechanism.
authors.affiliation: Department of Surgery, Karolinska Hospital, Stockholm, Sweden. Jesper.Lagergren@ks.se
authors.forename: J
authors.initials: J
authors.lastname: Lagergren
authors.forename: W
authors.initials: W
authors.lastname: Ye
authors.forename: A
authors.initials: A
authors.lastname: Ekbom
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology* / Q000601:surgery*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001646:Bile; D002276:Carcinoid Tumor / Q000453:epidemiology / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D017081:Cholecystectomy, Laparoscopic / Q000706:statistics & numerical data*; D002769:Cholelithiasis / Q000453:epidemiology / Q000601:surgery; D015331:Cohort Studies; D003106:Colon; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000601:surgery; D003135:Common Bile Duct; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007414:Intestinal Neoplasms / Q000453:epidemiology* / Q000601:surgery*; D007421:Intestine, Small; D008297:Male; D008875:Middle Aged; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology