title: Risk of oesophageal cancer by histology among patients hospitalised for gastroduodenal ulcers.
abstract: OBJECTIVE
  The mechanism behind the epidemiologically evident inverse relation between Helicobacter pylori seropositivity and risk of oesophageal adenocarcinoma (OAC) remains obscure. Severe corpus gastritis is unlikely to be in the causal pathway. With the hypothesis of a uniformly low risk, the associations of OAC with duodenal ulcer and gastric ulcer were explored, both linked to H pylori infection but with different patterns of bacterial colonisation and intragastric acidity. Possible associations of oesophageal squamous cell carcinoma (OSCC) with these ulcer types were also addressed.
  
  
  METHODS
  Retrospective cohorts of 61,548 and 81,379 unoperated patients with duodenal ulcer and gastric ulcer, respectively, recorded in the Swedish Inpatient Register since 1965, were followed from the first hospitalisation until the date of any cancer, death, emigration, definitive surgery, or 31 December 2003. Standardised incidence ratios (SIRs), with 95% CIs, expressed relative risk of oesophageal cancer, compared with the Swedish population matched for age, sex and calendar period.
  
  
  RESULTS
  Contrary to expectation, patients with duodenal ulcer had a significant 70% excess risk of OAC (SIR 1.7, 95% CI 1.1 to 2.5). Gastric ulcer was unrelated to OAC (SIR 1.1, 95% CI 0.6 to 1.7). Although duodenal ulcer was non-significantly associated with a small excess of OSCC (SIR 1.3, 95% CI 0.96 to 1.8), gastric ulcer was linked to 80% increased risk (SIR 1.8, 95% CI 1.4 to 2.3).
  
  
  CONCLUSIONS
  The inverse association between H pylori and OAC does not pertain to all infections. The pattern of gastric colonisation and/or impact on acidity may be important. With the reservation for the possibility of confounding, this study also provides some support for the importance of intragastric environment in the aetiology of OSCC.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, SE 171 77, Stockholm, Sweden. Shahram.bahmanyar@ki.se
authors.forename: Shahram
authors.initials: S
authors.lastname: Bahmanyar
authors.forename: Kazem
authors.initials: K
authors.lastname: Zendehdel
authors.forename: Olof
authors.initials: O
authors.lastname: Nyrén
authors.forename: Weimin
authors.initials: W
authors.lastname: Ye
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology / Q000209:etiology*; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology / Q000209:etiology*; D004381:Duodenal Ulcer / Q000150:complications* / Q000453:epidemiology; D004812:Epidemiologic Methods; D004938:Esophageal Neoplasms / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D013276:Stomach Ulcer / Q000150:complications* / Q000453:epidemiology; D013548:Sweden / Q000453:epidemiology