title: Hormone replacement therapy and breast cancer: heterogeneous risks by race, weight, and breast density.
abstract: BACKGROUND
  Although studies have demonstrated a positive association between hormone replacement therapy (HRT) and breast cancer risk, this association may vary by patient factors.
  
  
  METHODS
  We analyzed 1642824 screening mammograms with 9300 breast cancer cases in postmenopausal women aged 45 years or older derived from the Breast Cancer Surveillance Consortium, a longitudinal registry of mammography screening in the United States. Multiple imputation methods were used to accommodate missing data for HRT use (14%) and other covariables. We performed logistic regression to estimate odds ratios (ORs) for breast cancer associated with HRT use within strata of race/ethnicity, age, body mass index (BMI), and breast density, with two-way interaction terms between HRT use and each key covariable of interest. P values for assessing possible interactions were computed from Wald z statistics. All statistical tests were two-sided.
  
  
  RESULTS
  HRT use was associated with greater than 20% increased risk in white (OR = 1.21; 95% CI = 1.14 to 1.28), Asian (OR = 1.58; 95% CI = 1.18 to 2.11), and Hispanic women (OR = 1.35; 95% CI = 1.09 to 1.67) but not black women (OR = 0.91; 95% CI = 0.72 to 1.14; P interaction = .04). In women with low/normal BMI and extremely dense breasts, HRT use was associated with the highest breast cancer risk (OR = 1.49; 95% CI = 1.21 to 1.83), compared with nonusers. In overweight/obese women with less-dense breasts, no excess risk was associated with HRT use (adjusted ORs = 0.96 to 1.03).
  
  
  CONCLUSIONS
  The impact of HRT use on breast cancer risk varies according to race/ethnicity, BMI, and breast density. This risk stratification could help in advising HRT use for the relief of menopausal symptoms.
authors.affiliation: Affiliations of authors: Department of Health Studies (NH, JJD, DH) and Department of Medicine and Center for Clinical Cancer Genetics (SH, OIO), University of Chicago, Chicago, IL; Center for Injury Research and Prevention, Children's Hospital of Philadelphia, Philadelphia, PA (WW).
authors.forename: Ningqi
authors.initials: N
authors.lastname: Hou
authors.forename: Susan
authors.initials: S
authors.lastname: Hong
authors.forename: Wenli
authors.initials: W
authors.lastname: Wang
authors.forename: Olufunmilayo I
authors.initials: OI
authors.lastname: Olopade
authors.forename: James J
authors.initials: JJ
authors.lastname: Dignam
authors.forename: Dezheng
authors.initials: D
authors.lastname: Huo
mesh_terms: D001741:Black or African American / Q000706:statistics & numerical data; D000368:Aged; D001213:Asian / Q000706:statistics & numerical data; D015992:Body Mass Index; D001835:Body Weight; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000139:chemically induced / Q000000981:diagnostic imaging / Q000208:ethnology* / Q000209:etiology*; D055088:Early Detection of Cancer / Q000379:methods; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D005260:Female; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008327:Mammography; D008875:Middle Aged; D016017:Odds Ratio; D017698:Postmenopause; D044469:Racial Groups; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data