title: Predictors of breast density change after hormone therapy cessation: results from a randomized trial.
abstract: BACKGROUND
  Postmenopausal hormone therapy cessation is associated with a decrease in mammographic density (MD), but it is unknown whether this effect is modified by woman-level characteristics. We investigated whether we could identify characteristics of women who were most likely to experience a decrease in MD due to hormone therapy cessation.
  
  
  METHODS
  Postmenopausal hormone therapy users with a prior screening mammogram (n = 1,168) were randomized to continue hormone therapy or to suspend hormone therapy for 1 month or 2 months before their next screening mammogram. We estimated relative risks (RR) and attributable risks with 95% CIs of a ≥7.5% decrease in percentage MD (%MD) versus no change associated with hormone therapy cessation, stratified by age, body mass index (BMI), parity, and other factors.
  
  
  RESULTS
  Hormone therapy cessation increased a woman's likelihood of experiencing a ≥7.5% decrease in %MD by 30% (95% CI = 1.03-1.7), but we found little evidence of effect modification by age, race, BMI, change in BMI, baseline %MD, parity, family history of breast cancer, hormone therapy type, or duration of hormone therapy use.
  
  
  CONCLUSIONS
  Woman-level factors do not appear to explain why some women experience a decrease in %MD following hormone therapy cessation and others do not.
  
  
  CONCLUSIONS
  We were unable to identify subgroups of women who are more likely to experience a decrease in MD due to hormone therapy cessation; other factors, such as genetic factors, may be important determinants of hormone therapy-related changes in MD.
authors.affiliation: Group Health Cooperative, Group Health Research Institute, Seattle, WA 98101, USA. lowry.s@ghc.org
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Lowry
authors.forename: Erin J
authors.initials: EJ
authors.lastname: Aiello Bowles
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Anderson
authors.forename: Diana S M
authors.initials: DS
authors.lastname: Buist
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001940:Breast / Q000187:drug effects* / Q000473:pathology*; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D020249:Hormone Replacement Therapy; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D017698:Postmenopause; D011379:Prognosis; D012306:Risk; D012307:Risk Factors