title: Postmenopausal hormone therapy is associated with in situ breast cancer risk.
abstract: BACKGROUND
  The relationship between postmenopausal hormone therapy (HT) and invasive breast cancer has been extensively investigated, but that with breast carcinoma in situ (BCIS) has received relatively little attention. The aim of our present study was to review and summarize the evidence provided by longitudinal studies on the association between postmenopausal HT use and BCIS risk.
  
  
  METHODS
  A comprehensive literature search for articles published up to May 2012 was performed. Prior to performing a meta-analysis, the studies were evaluated for publication bias and heterogeneity. Relative risk (RR) or odds ratio (OR) values were calculated using 14 reports (8 case-control studies and 6 cohort studies), published between 1986 and 2012.
  
  
  RESULTS
  There was evidence of an association between ever postmenopausal estrogen use and BCIS based on a random-effects model (RR = 1.25, 95% confidence interval (CI) = 1.01, 1.55). However, we found no strong evidence of an association between ever postmenopausal estrogen combined with progesterone use and BCIS using a random- effects model (RR = 1.55, 95% CI = 0.95, 2.51). Furthermore, our analysis showed a strong association between " > 5 years duration" of estrogen or estrogen combined with progesterone use and BCIS. Furthermore, current use of any HT is associated with increased risk of BCIS in cohort studies. Additional well-designed large studies are now required to validate this association in different populations.
authors.affiliation: Department of Breast Surgery, First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Xiao-Jian
authors.initials: XJ
authors.lastname: Ni
authors.forename: Tian-Song
authors.initials: TS
authors.lastname: Xia
authors.forename: Ying-Chun
authors.initials: YC
authors.lastname: Zhao
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Ma
authors.forename: Jie
authors.initials: J
authors.lastname: Zhao
authors.forename: Xiao-An
authors.initials: XA
authors.lastname: Liu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Ding
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Zha
authors.forename: Shui
authors.initials: S
authors.lastname: Wang
mesh_terms: D001943:Breast Neoplasms / Q000209:etiology*; D018270:Carcinoma, Ductal, Breast / Q000209:etiology*; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000209:etiology*; D016022:Case-Control Studies; D015331:Cohort Studies; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D005260:Female; D006801:Humans; D017698:Postmenopause; D012307:Risk Factors