title: Coffee consumption and urologic cancer risk: a meta-analysis of cohort studies.
abstract: OBJECTIVE
  Controversial results were reported among several epidemiologic studies on the relationship between coffee consumption and urologic cancer risk. We, therefore, conducted this meta-analysis to clarify these associations.
  
  
  METHODS
  Electronic databases including Pubmed, Embase and Cochrane library were searched between January 1966 and August 2013 for eligible studies. Pooled relative risk (RR) and its 95 % confidence interval (CI) were calculated. All P values are two tailed.
  
  
  RESULTS
  Thirteen cohorts were eligible for inclusion. As to prostate cancer (PCa), significant reverse association was found among highest versus none/lowest analysis with acceptable heterogeneity (RR 0.86, 95 % CI 0.79-0.95; I(2) 25 %, P value for heterogeneity: 0.221). A pooled RR which assessed advanced PCa was 0.73 (with 95 % CI 0.50-1.07), and a slight stronger reverse association was found in fatal PCa. However, a slight insignificant reverse association, basing on 8 studies with 9 outcomes, was found in dose-response analysis (RR 0.98, 95 % CI 0.93-1.03). For kidney and bladder cancer, insignificant associations were found in both highest versus none/lowest analyses and dose-response analyses.
  
  
  CONCLUSIONS
  Our findings suggest that coffee consumption may reduce the risk of PCa. No associations were found with both bladder and kidney cancer. Further well-designed large-scaled cohort studies are warranted to provide more definitive conclusions.
authors.affiliation: Department of Urology, Shanghai Tenth People's Hospital, Tongji University, 301 Yanchang Road, Shanghai, 200072, China.
authors.forename: Tian-bao
authors.initials: TB
authors.lastname: Huang
authors.forename: Zhui-feng
authors.initials: ZF
authors.lastname: Guo
authors.forename: Xiao-long
authors.initials: XL
authors.lastname: Zhang
authors.forename: Xiao-peng
authors.initials: XP
authors.lastname: Zhang
authors.forename: Huan
authors.initials: H
authors.lastname: Liu
authors.forename: Jiang
authors.initials: J
authors.lastname: Geng
authors.forename: Xu-dong
authors.initials: XD
authors.lastname: Yao
authors.forename: Jun-hua
authors.initials: JH
authors.lastname: Zheng
mesh_terms: D003069:Coffee / Q000009:adverse effects; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000453:epidemiology*; D008297:Male; D016017:Odds Ratio; D011471:Prostatic Neoplasms / Q000453:epidemiology*; D001749:Urinary Bladder Neoplasms / Q000453:epidemiology*
chemical_list: D003069:Coffee