title: Vitamin D and calcium supplementation and one-year change in mammographic density in the women's health initiative calcium and vitamin D trial.
abstract: BACKGROUND
  Calcium and vitamin D may be inversely related to breast cancer risk, in part by affecting mammographic density. However, results from previous, mostly cross-sectional studies have been mixed, and there have been few randomized clinical trials of the effect of calcium and vitamin D supplementation on change in mammographic density.
  
  
  METHODS
  We assessed the effect of one year of supplementation on mammographic density in 330 postmenopausal women enrolled in the Women's Health Initiative hormone therapy (HT) and calcium and vitamin D (CaD) trials. Women were randomized to receive 1,000 mg/d of elemental calcium carbonate plus 400 IU/d of vitamin D(3) or placebo.
  
  
  RESULTS
  After approximately one year, mammographic density decreased 2% in the CaD supplementation group and increased 1% in the placebo group (ratio of means = 0.97; 95% CI = 0.81-1.17). Results suggested potential interaction by HT use (P = 0.08). Among women randomized to HT placebo, the ratio of mean density comparing CaD supplementation and placebo groups was 0.82 (95% CI = 0.61-1.11) vs. 1.16 (95% CI = 0.92-1.45) in women randomized to active HT. In sensitivity analyses limited to women taking ≥ 80% of study supplements, ratios were 0.67 (95% CI = 0.41-1.07) in women not assigned to HT and 1.07 (95% CI = 0.79-1.47) women assigned to HT.
  
  
  CONCLUSIONS
  We observed no overall effect of vitamin D and calcium supplementation on mammographic density after one year.
  
  
  CONCLUSIONS
  Potential interaction between these nutrients and estrogen as related to mammographic density warrants further study.
authors.affiliation: Division ofBiostatistics and Epidemiology,University of Massachusetts, Amherst, Massachusetts 01003, USA. ebertone@schoolph.umass.edu
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Bertone-Johnson
authors.forename: Anne
authors.initials: A
authors.lastname: McTiernan
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Thomson
authors.forename: Jean
authors.initials: J
authors.lastname: Wactawski-Wende
authors.forename: Aaron K
authors.initials: AK
authors.lastname: Aragaki
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Rohan
authors.forename: Mara Z
authors.initials: MZ
authors.lastname: Vitolins
authors.forename: Rulla M
authors.initials: RM
authors.lastname: Tamimi
authors.forename: Karen C
authors.initials: KC
authors.lastname: Johnson
authors.forename: Dorothy
authors.initials: D
authors.lastname: Lane
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Rexrode
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Peck
authors.forename: Rowan T
authors.initials: RT
authors.lastname: Chlebowski
authors.forename: Gloria
authors.initials: G
authors.lastname: Sarto
authors.forename: Joann E
authors.initials: JE
authors.lastname: Manson
mesh_terms: D000368:Aged; D001940:Breast / Q000166:cytology* / Q000187:drug effects*; D001943:Breast Neoplasms / Q000178:diet therapy / Q000517:prevention & control*; D002136:Calcium, Dietary / Q000008:administration & dosage*; D016022:Case-Control Studies; D002762:Cholecalciferol / Q000008:administration & dosage*; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause; D011379:Prognosis; D016387:Women's Health
chemical_list: D002136:Calcium, Dietary; D002762:Cholecalciferol