title: Endoscopic sphincterotomy and risk of malignancy in the bile ducts, liver, and pancreas.
abstract: OBJECTIVE
  After endoscopic sphincterotomy (ES), an elevated long-term risk of cholangiocarcinoma has been reported. However, large population-based studies testing this hypothesis are lacking. The aim of this study was to evaluate the risk in a large population-based cohort.
  
  
  METHODS
  Data concerning all patients having had an inpatient endoscopic retrograde cholangiopancreatography (ERCP) were collected from the Swedish Hospital Discharge Register. Incident cases of malignancy were identified through linkage to the Swedish Cancer Registry. Patients with a diagnosis of malignancy before or within 2 years of the ERCP were excluded. The cohort was followed to a diagnosis of malignancy, censoring as a result of death, emigration, or end of follow-up. The risk of malignancy was calculated as standardized incidence ratio (SIR) compared with the general population, inherently adjusting for age, gender, and year of entry.
  
  
  RESULTS
  A total of 27,708 patients undergoing ERCP from 1976 through 2003 for benign disease were included in the cohort. ES was performed in 11,617 of these. The risk of malignancy in the bile ducts alone and in the bile ducts, liver, and pancreas together was significantly elevated in the total cohort (SIR, 3.3; 95% confidence interval, 2.3-4.5), irrespective of whether an ES was performed. The risk of malignancy diminished with increasing follow-up time. Patients ever having had a cholecystectomy had a significantly lower risk of the studied malignancies.
  
  
  CONCLUSIONS
  The risk of malignancy in the bile ducts, liver, or pancreas is elevated after ERCP in benign disease. However, ES does not seem to affect this risk.
authors.affiliation: Department of Clinical Science, Intervention and Technology, Karolinska Institute, Stockholm, Sweden. cecilia.stromberg@karolinska.se
authors.forename: Cecilia
authors.initials: C
authors.lastname: Strömberg
authors.forename: Juhua
authors.initials: J
authors.lastname: Luo
authors.forename: Lars
authors.initials: L
authors.lastname: Enochsson
authors.forename: Urban
authors.initials: U
authors.lastname: Arnelo
authors.forename: Magnus
authors.initials: M
authors.lastname: Nilsson
mesh_terms: D000368:Aged; D001650:Bile Duct Neoplasms / Q000453:epidemiology*; D002760:Cholangiopancreatography, Endoscopic Retrograde / Q000009:adverse effects*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008113:Liver Neoplasms / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000453:epidemiology*; D012307:Risk Factors; D016717:Sphincterotomy, Endoscopic / Q000009:adverse effects*; D013548:Sweden; D013997:Time Factors