title: Green tea consumption and gastric cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population.
abstract: OBJECTIVE
  Numerous in vitro and animal studies have shown that green tea has a protective effect against cancer. However, results from epidemiologic studies are conflicting. We evaluated the association between green tea consumption and risk for gastric cancer risk among the Japanese population based on a systematic review of epidemiologic evidence.
  
  
  METHODS
  Original data were obtained from MEDLINE searches using PubMed or from searches of the Ichushi database, complemented with manual searches. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biologic plausibility.
  
  
  RESULTS
  Eight cohort studies and three case-control studies were identified. Overall, we found no preventive effect on gastric cancer for green tea intake in cohort studies. However, a small, consistent risk reduction limited to women was observed, which was confirmed by pooling data of six cohort studies (hazard ratio = 0.79, 95% confidence interval 0.65-0.96 with ≥5 cups/day of green tea intake). Case-control studies consistently showed a weak inverse association between green tea intake and gastric cancer risk.
  
  
  CONCLUSIONS
  We conclude that green tea possibly decreases the risk of gastric cancer in women. However, epidemiologic evidence is still insufficient to demonstrate any association in men.
authors.affiliation: Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, 5-1-1 Tsukiji Chuo-ku, Tokyo 104-0045 Japan. ssasazuk@ncc.go.jp
authors.forename: Shizuka
authors.initials: S
authors.lastname: Sasazuki
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
authors.forename: Keitaro
authors.initials: K
authors.lastname: Matsuo
authors.forename: Hidemi
authors.initials: H
authors.lastname: Ito
authors.forename: Kenji
authors.initials: K
authors.lastname: Wakai
authors.forename: Chisato
authors.initials: C
authors.lastname: Nagata
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Mizoue
authors.forename: Keitaro
authors.initials: K
authors.lastname: Tanaka
authors.forename: Ichiro
authors.initials: I
authors.lastname: Tsuji
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Tsugane
mesh_terms: D044466:Asian People; D005260:Female; D006801:Humans; D008297:Male; D040242:Risk Reduction Behavior; D013274:Stomach Neoplasms / Q000453:epidemiology*; D013662:Tea
chemical_list: D013662:Tea