title: Coffee and caffeine intake and breast cancer risk: an updated dose-response meta-analysis of 37 published studies.
abstract: OBJECTIVE
  We conducted an updated meta-analysis to summarize the evidence from published studies regarding the association of coffee and caffeine intake with breast cancer risk.
  
  
  METHODS
  Pertinent studies were identified by a search of PubMed and by reviewing the reference lists of retrieved articles. The fixed or random effect model was used based on heterogeneity test. The dose-response relationship was assessed by restricted cubic spline model and multivariate random-effect meta-regression.
  
  
  RESULTS
  37 published articles, involving 59,018 breast cancer cases and 966,263 participants, were included in the meta-analysis. No significant association was found between breast cancer risk and coffee (RR=0.97, P=0.09), decaffeinated coffee (RR=0.98, P=0.55) and caffeine (RR=0.99, P=0.73), respectively. And the association was still not significant when combining coffee and caffeine (coffee/caffeine) (RR=0.97, P=0.09). However, an inverse association of coffee/caffeine with breast cancer risk was found for postmenopausal women (RR=0.94, P=0.02), and a strong and significant association of coffee with breast cancer risk was found for BRCA1 mutation carriers (RR=0.69, P<0.01). A linear dose-response relationship was found for breast cancer risk with coffee and caffeine, and the risk of breast cancer decreased by 2% (P=0.05) for every 2 cups/day increment in coffee intake, and 1% (P=0.52) for every 200mg/day increment in caffeine intake, respectively.
  
  
  CONCLUSIONS
  Findings from this meta-analysis suggested that coffee/caffeine might be weakly associated with breast cancer risk for postmenopausal women, and the association for BRCA1 mutation carriers deserves further investigation.
authors.affiliation: Department of Epidemiology and Health Statistics, the Medical College of Qingdao University, Shandong, Qingdao, Dongzhou Road No. 38, PR China. jiangwjqd@yahoo.com.cn
authors.forename: Wenjie
authors.initials: W
authors.lastname: Jiang
authors.forename: Yili
authors.initials: Y
authors.lastname: Wu
authors.forename: Xiubo
authors.initials: X
authors.lastname: Jiang
mesh_terms: D001943:Breast Neoplasms / Q000139:chemically induced / Q000453:epidemiology* / Q000235:genetics; D002110:Caffeine / Q000008:administration & dosage*; D016022:Case-Control Studies; D003069:Coffee; D004305:Dose-Response Relationship, Drug; D005260:Female; D019398:Genes, BRCA1; D006801:Humans; D009154:Mutation; D017698:Postmenopause
chemical_list: D003069:Coffee; D002110:Caffeine