title: Green tea consumption and stomach cancer risk: a meta-analysis.
abstract: OBJECTIVE
  Green tea has been suggested to have a chemopreventive effect against various cancers including stomach cancer. The aim of this study is to elucidate the relationship between green tea consumption and stomach cancer risk by meta-analysis.
  
  
  METHODS
  Eighteen observational studies were identified using MEDLINE, THE COCHRANE LIBRARY, RISS, and a manual search. Summary relative risks/odds ratios (RR/ORs) for the highest versus non/lowest green tea consumption levels were calculated on the basis of fixed and random effect models. Subgroup analyses were used to examine heterogeneity across the studies.
  
  
  RESULTS
  The combined results indicate a reduced risk of stomach cancer with intake of green tea (RR/OR=0.86, 95% CI=0.74-1.00). Subgroup analysis with six studies that reported differences between the highest and lowest consumption levels equal to or greater than five cups/day revealed a statistically significant protective effect (RR/OR=0.68, 95% CI=0.53-0.87).
  
  
  CONCLUSIONS
  Green tea appears to play a protective role against the development of stomach cancer. The results also suggest that a higher level of green tea consumption might be needed for a clear preventive effect to appear. This conclusion, however, should be interpreted with caution because various biases can affect the results of a meta-analysis.
authors.affiliation: Department of Epidemiology and Biostatistics, Graduate School of Public Health, Yonsei University, Seoul, Korea.
authors.forename: Hyunseok
authors.initials: H
authors.lastname: Kang
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Rha
authors.forename: Kyung Won
authors.initials: KW
authors.lastname: Oh
authors.forename: Chung Mo
authors.initials: CM
authors.lastname: Nam