title: Breast cancer risk by breast density, menopause, and postmenopausal hormone therapy use.
abstract: OBJECTIVE
  We determined whether the association between breast density and breast cancer risk and cancer severity differs according to menopausal status and postmenopausal hormone therapy (HT) use.
  
  
  METHODS
  We collected data on 587,369 women who underwent 1,349,027 screening mammography examinations; 14,090 women were diagnosed with breast cancer. We calculated 5-year breast cancer risk from a survival model for subgroups of women classified by their Breast Imaging Reporting and Data System (BIRADS) breast density, age, menopausal status, and current HT use, assuming a body mass index of 25 kg/m(2). Odds of advanced (ie, IIb, III, IV) versus early (ie, I, IIa) stage invasive cancer was calculated according to BIRADS density.
  
  
  RESULTS
  Breast cancer risk was low among women with low density (BIRADS-1): women age 55 to 59 years, 5-year risk was 0.8% (95% CI, 0.6 to 0.9%) for non-HT users and 0.9% (95% CI, 0.7% to 1.1%) for estrogen and estrogen plus progestin users. Breast cancer risk was high among women with very high density (BIRADS-4), particularly estrogen plus progestin users: women age 55 to 59 years, 5-year risk was 2.4% (95% CI, 2.0% to 2.8%) for non-HT users, 3.0% (95% CI, 2.6% to 3.5%) for estrogen users, and 4.2% (95% CI, 3.7% to 4.6%) for estrogen plus progestin users. Advanced-stage breast cancer risk was increased 1.7-fold for postmenopausal HT users who had very high density (BIRADS-4) compared to those with average density (BIRADS-2).
  
  
  CONCLUSIONS
  Postmenopausal women with high breast density are at increased risk of breast cancer and should be aware of the added risk of taking HT, especially estrogen plus progestin.
authors.affiliation: General Internal Medicine Section, University of California, San Francisco Coordinating Center, California Pacific Medical Center Research Institute, San Francisco, CA, USA. Karla.Kerlikowske@ucsf.edu
authors.forename: Karla
authors.initials: K
authors.lastname: Kerlikowske
authors.forename: Andrea J
authors.initials: AJ
authors.lastname: Cook
authors.forename: Diana S M
authors.initials: DS
authors.lastname: Buist
authors.forename: Steve R
authors.initials: SR
authors.lastname: Cummings
authors.forename: Celine
authors.initials: C
authors.lastname: Vachon
authors.forename: Pamela
authors.initials: P
authors.lastname: Vacek
authors.forename: Diana L
authors.initials: DL
authors.lastname: Miglioretti
mesh_terms: D000367:Age Factors; D000368:Aged; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000139:chemically induced* / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D004967:Estrogens / Q000008:administration & dosage / Q000009:adverse effects; D005260:Female; D006801:Humans; D008327:Mammography; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D017698:Postmenopause; D011372:Progestins / Q000008:administration & dosage / Q000009:adverse effects; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index
chemical_list: D004967:Estrogens; D011372:Progestins