title: Isoflavone intake and risk of gastric cancer: a population-based prospective cohort study in Japan.
abstract: BACKGROUND
  Isoflavones are structurally similar to 17β-estradiol and may be able to prevent gastric cancer. However, there is contradictory evidence concerning the relation between the intake of soy food, which is rich in isoflavones, and gastric cancer. The association with gastric cancer might differ between isoflavones and soy foods, and research on the effects of isoflavone intake alone on gastric cancer is needed.
  
  
  OBJECTIVE
  We investigated the association between isoflavone intake and the incidence of gastric cancer.
  
  
  METHODS
  We conducted a large, population-based prospective study of 39,569 men and 45,312 women aged 45-74 y. Dietary soy and isoflavone intakes were measured by using a validated food-frequency questionnaire in 1995 and 1998.
  
  
  RESULTS
  During 806,550 person-years of follow-up, we identified 1249 new gastric cancer cases. Isoflavone intake was not associated with gastric cancer in either men or women. Compared with the lowest quartile, the HR and 95% CI for developing gastric cancer in the fourth quartile of isoflavone intake was 1.00 (0.81, 1.24) for men and 1.07 (0.77, 1.50) for women. In a stratified analysis by exogenous female hormones (women only), however, we found an increasing trend in risk of gastric cancer associated with higher isoflavone intakes among exogenous female hormone users (P-trend = 0.03) but not for nonusers (P-interaction = 0.04).
  
  
  CONCLUSIONS
  The current study does not support the hypothesis that higher intakes of isoflavones prevent gastric cancer in either men or women.
authors.affiliation: Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, Japan.
authors.forename: Azusa
authors.initials: A
authors.lastname: Hara
authors.forename: Shizuka
authors.initials: S
authors.lastname: Sasazuki
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.forename: Motoki
authors.initials: M
authors.lastname: Iwasaki
authors.forename: Taichi
authors.initials: T
authors.lastname: Shimazu
authors.forename: Norie
authors.initials: N
authors.lastname: Sawada
authors.forename: Taiki
authors.initials: T
authors.lastname: Yamaji
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Tsugane
mesh_terms: D000368:Aged; D004032:Diet; D004034:Diet Surveys; D015914:Estrogen Replacement Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007529:Isoflavones / Q000494:pharmacology*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D028321:Plant Preparations / Q000737:chemistry / Q000494:pharmacology*; D011446:Prospective Studies; D012306:Risk; D045730:Soy Foods; D013025:Glycine max / Q000737:chemistry*; D013274:Stomach Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D011795:Surveys and Questionnaires
chemical_list: D007529:Isoflavones; D028321:Plant Preparations