title: Association between breastfeeding and breast cancer risk: evidence from a meta-analysis.
abstract: BACKGROUND
  Quantification of the association between breastfeeding and breast cancer risk is still conflicting. Therefore, we conducted a meta-analysis to summarize the evidence from epidemiological studies of breastfeeding with the risk of breast cancer.
  
  
  METHODS
  Pertinent studies were identified by a search of PubMed between January 1, 2008 and July 31, 2014. The random-effect model was used. Sensitivity analysis, subgroups analysis, and publication bias were conducted.
  
  
  RESULTS
  Twenty-four articles with 27 studies involving 13,907 breast cancer cases were included in this meta-analysis. Pooled results suggested that breastfeeding was inversely [corrected] associated with the risk of breast cancer. The summary relative risk (RR) of breast cancer for the ever compared with never categories of breastfeeding was 0.613 (95% confidence interval [CI], 0.442-0.850). An inverse association was also found for the longest compared with the shortest categories of breastfeeding with the risk of breast cancer (RR=0.471; 95% CI, 0.368-0.602). No evidence of publication bias was found.
  
  
  CONCLUSIONS
  Findings from this meta-analysis suggest that breastfeeding, particularly a longer duration of breastfeeding, was inversely associated with risk of breast cancer.
authors.affiliation: Department of Oncology, East Hospital, Tongji University School of Medicine , Shanghai, China .
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhou
authors.forename: Jingde
authors.initials: J
authors.lastname: Chen
authors.forename: Qun
authors.initials: Q
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.forename: Haifeng
authors.initials: H
authors.lastname: Lan
authors.forename: Hong
authors.initials: H
authors.lastname: Jiang
mesh_terms: D000328:Adult; D001942:Breast Feeding / Q000379:methods*; D001943:Breast Neoplasms / Q000209:etiology / Q000517:prevention & control*; D000075202:Contraindications; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D016017:Odds Ratio; D011247:Pregnancy; D012307:Risk Factors; D013997:Time Factors