title: Menstrual and reproductive risk factors and risk for gastric adenocarcinoma in women: findings from the canadian national enhanced cancer surveillance system.
abstract: OBJECTIVE
  The role of menstrual and reproductive risk factors for gastric cancer has not been well studied.
  
  
  METHODS
  This population-based case-control study included 326 women aged 20 to 74 years with gastric adenocarcinoma. Controls were 326 women frequency matched on age. Data for reproductive and/or hormonal exposure and gastric cancer risk factors were captured through self-administered questionnaire.
  
  
  RESULTS
  Later age at menarche was associated with increased risk for adenocarcinoma compared with menarche onset at younger than 13 years of age (13 to 14 years: odds ratio [OR], 1.45; 95% confidence interval [CI], 1.00-2.10; > or =15 years: OR, 1.93; 95% CI, 1.19-3.13). Compared with premenopause, natural menopause was associated with increased risk for adenocarcinoma (OR, 1.99; 95% CI, 0.98-4.05). Compared with nulliparity, 4 or more births were associated with decreased risk for gastric cancer, as was being pregnant for 5 months or longer if the first pregnancy occurred at younger than 24 years (OR, 0.55; 95% CI, 0.31-0.96) or 25 years or older (OR, 0.67; 95% CI, 0.38-1.18). Oral contraceptives and hormone replacement therapy were associated with a non-statistically significant decreased risk.
  
  
  CONCLUSIONS
  These findings suggest that hormonal factors associated with greater exposure to estrogen and/or progesterone may be associated with decreased risk for gastric cancer.
authors.affiliation: Drug Safety Department, AstraZeneca, Mississauga, Toronto, Ontario, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Frise
authors.forename: Nancy
authors.initials: N
authors.lastname: Kreiger
authors.forename: Steven
authors.initials: S
authors.lastname: Gallinger
authors.forename: George
authors.initials: G
authors.lastname: Tomlinson
authors.forename: Michelle
authors.initials: M
authors.lastname: Cotterchio
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology* / Q000209:etiology; D000328:Adult; D000368:Aged; D002170:Canada / Q000453:epidemiology; D016022:Case-Control Studies; D003278:Contraceptives, Oral, Hormonal / Q000009:adverse effects; D005260:Female; D020249:Hormone Replacement Therapy / Q000009:adverse effects; D006801:Humans; D016015:Logistic Models; D008572:Menarche; D008593:Menopause; D008597:Menstrual Cycle; D008875:Middle Aged; D010298:Parity; D011247:Pregnancy; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000453:epidemiology* / Q000209:etiology
chemical_list: D003278:Contraceptives, Oral, Hormonal