title: Association between green tea and colorectal cancer risk: a meta-analysis of 13 case-control studies.
abstract: OBJECTIVE
  Experimental studies have suggested green tea to be a chemopreventive agent for colorectal cancer, and many studies have examined possible associations. However, the conclusions were inconsistent or even contradictory, so we performed a meta-analysis based on published case-control studies to explore if green tea is indeed a protective factor.
  
  
  METHODS
  PubMed was searched up to May 10th, 2012 for relevant studies, and references of included studies were manually searched. Finally 13 eligible studies, involving 12,636 cases and 38,419 controls were identified. After data extraction, a meta-analysis was performed using CMA v2 software.
  
  
  RESULTS
  The results indicated there may be a weak but not statistically significant reduced risk of colorectal cancer with high dose of green tea intake (OR=0.95, 95% CI:0.81-1.11, p=0.490.69-0.98). This protective effect was also found in all subgroups, except in American and European populations. Sensitivity analysis indicated the result to be robust. Publication bias was not detected by either funnel plot or Egger tests.
  
  
  CONCLUSIONS
  The results of this meta-analysis indicate a weak lower tendency for colorectal cancer development with green tea consumption, but available epidemiologic data are insufficient to conclude that green tea may protect against colorectal cancer in humans.
authors.affiliation: Department of Emergency, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei Province, China.
authors.forename: Xue-Jun
authors.initials: XJ
authors.lastname: Wang
authors.forename: Xian-Tao
authors.initials: XT
authors.lastname: Zeng
authors.forename: Xiao-Li
authors.initials: XL
authors.lastname: Duan
authors.forename: Huan-Chao
authors.initials: HC
authors.lastname: Zeng
authors.forename: Rui
authors.initials: R
authors.lastname: Shen
authors.forename: Ping
authors.initials: P
authors.lastname: Zhou
mesh_terms: D001628:Beverages; D028241:Camellia sinensis / Q000737:chemistry*; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D006801:Humans; D010936:Plant Extracts / Q000008:administration & dosage*; D012306:Risk; D013662:Tea
chemical_list: D010936:Plant Extracts; D013662:Tea