title: Worldwide Inverse Association between Gastric Cancer and Esophageal Adenocarcinoma Suggesting a Common Environmental Factor Exerting Opposing Effects.
abstract: OBJECTIVE
  The incidence of esophageal adenocarcinoma (EAC) is increasing while adenocarcinoma of the stomach is decreasing. We have investigated whether the incidences of these two cancers and their time trends might be inversely related pointing to a common environmental factor exerting opposite effects on these cancers.
  
  
  METHODS
  For cross-sectional analyses data were abstracted from "Cancer Incidence in Five Continents" (CI5) Volume X and GLOBOCAN 2012. Relevant ICD-10 codes were used to locate esophageal and gastric cancers anatomically, and ICD-O codes for the histological diagnosis of EAC. For longitudinal analyses, age standardized rates (ASRs) of EAC and total gastric cancer (TGC) were extracted from CI5C-Plus.
  
  
  RESULTS
  Estimated (2012) ASRs were available for 51 countries and these showed significant negative correlations between EAC and both TGC (males: correlation coefficient (CC)=-0.38, P=0.006, females: CC=-0.41, P=0.003) and non-cardia gastric cancer rates (males: CC=-0.41, P=0.003 and females: CC=-0.43, P=0.005). Annual incidence trends were analyzed for 38 populations through 1989-2007 and showed significant decreases for TGC in 89% and increases for EAC in 66% of these, with no population showing a fall in the latter. Significant negative correlation between the incidence trends of the two cancers was observed in 27 of the 38 populations over the 19-50 years of available paired data. Super-imposition of the longitudinal and cross-sectional data indicated that populations with a current high incidence of EAC and low incidence of gastric cancer had previously resembled countries with a high incidence of gastric cancer and low incidence of EAC.
  
  
  CONCLUSIONS
  The negative association between gastric cancer and EAC in both current incidences and time trends is consistent with a common environmental factor predisposing to one and protecting from the other.
authors.affiliation: Section of Gastroenterology, Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Mohammad H
authors.initials: MH
authors.lastname: Derakhshan
authors.affiliation: Section of Cancer Surveillance, International Agency for Research on Cancer, Lyon, France.
authors.forename: Melina
authors.initials: M
authors.lastname: Arnold
authors.affiliation: Scottish Cancer Registry, NHS Scotland, Edinburgh, UK.
authors.forename: David H
authors.initials: DH
authors.lastname: Brewster
authors.affiliation: Institute of Cancer Sciences, University of Glasgow, Glasgow, UK.
authors.forename: James J
authors.initials: JJ
authors.lastname: Going
authors.affiliation: Section of Gastroenterology, Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK.
authors.forename: David R
authors.initials: DR
authors.lastname: Mitchell
authors.affiliation: Section of Cancer Surveillance, International Agency for Research on Cancer, Lyon, France.
authors.forename: David
authors.initials: D
authors.lastname: Forman
authors.affiliation: Section of Gastroenterology, Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Kenneth E L
authors.initials: KE
authors.lastname: McColl
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology* / Q000473:pathology; D000367:Age Factors; D000368:Aged; D003430:Cross-Sectional Studies; D004781:Environmental Exposure / Q000706:statistics & numerical data; D004938:Esophageal Neoplasms / Q000453:epidemiology* / Q000473:pathology; D005260:Female; D014943:Global Health; D016481:Helicobacter Infections / Q000453:epidemiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012042:Registries; D012307:Risk Factors; D012737:Sex Factors; D013274:Stomach Neoplasms / Q000453:epidemiology* / Q000473:pathology