title: Estrogen alone and health outcomes in black women by African ancestry: a secondary analyses of a randomized controlled trial.
abstract: In postmenopausal black women in the Women's Health Initiative randomized trial, estrogen alone reduced breast cancers but its comprehensive influence on health outcomes in black women is unknown. Therefore, we examined this issue in the Women's Health Initiative overall and by African ancestry.
  
  
  
  A total of 1,616 black women with prior hysterectomy, including 1,061 with percent African ancestry determination, at 40 US centers were randomly assigned to conjugated equine estrogen (0.625 mg/d) or placebo for 7.2 years' (median) intervention with 13 years' cumulative follow-up. Coronary heart disease (CHD) and breast cancer were primary efficacy and safety outcomes, respectively. A global index also included stroke, colorectal cancer, hip fracture, pulmonary embolism, and death.
  
  
  
  Black women in the estrogen-alone group compared with black women in the placebo group had fewer breast cancers (17 vs 40, hazard ratio [HR] 0.47, 95% CI 0.26-0.82). In women with more than 80% African ancestry, breast cancer HR was lower (0.32, 95% CI 0.12-0.86, trend P = 0.04 for ancestry effect). Most other outcomes including CHD, stroke, hip fracture, and the global index were null with estrogen use in black women; a global index effect was more favorable in younger black women (HR 0.65, 95% CI 0.43-0.98).
  
  
  
  In black postmenopausal women with prior hysterectomy, estrogen alone significantly reduced breast cancer incidence with no adverse influence on CHD, venous thromboembolism, or all-cause mortality. Favorable estrogen-alone global index effects in younger black women warrant further study.
authors.affiliation: 1Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 2Division of Public Health Issues, Fred Hutchinson Cancer Research Center, Seattle, WA 3Brigham and Women's Hospital, Harvard Medical School, Boston, MA 4School of Medicine and Public Health, University of Wisconsin, Madison, WI 5Department of Obstetrics and Gynecology, University of Miami, Miami, FL 6Harbor-UCLA Medical Center, Department of Medicine, Torrance, CA 7School of Public Health, University of Pittsburgh, Pittsburgh, PA 8Division of Biostatistics, School of Medicine, University of California, Davis, CA 9College of Public Health, University of Iowa, Iowa City, IA.
authors.forename: Rowan T
authors.initials: RT
authors.lastname: Chlebowski
authors.forename: Wendy
authors.initials: W
authors.lastname: Barrington
authors.forename: Aaron K
authors.initials: AK
authors.lastname: Aragaki
authors.forename: JoAnn E
authors.initials: JE
authors.lastname: Manson
authors.forename: Gloria
authors.initials: G
authors.lastname: Sarto
authors.forename: Mary J
authors.initials: MJ
authors.lastname: OʼSullivan
authors.forename: Daniel
authors.initials: D
authors.lastname: Wu
authors.forename: Jane A
authors.initials: JA
authors.lastname: Cauley
authors.forename: Lihong
authors.initials: L
authors.lastname: Qi
authors.forename: Robert L
authors.initials: RL
authors.lastname: Wallace
authors.forename: Ross L
authors.initials: RL
authors.lastname: Prentice
mesh_terms: D001741:Black or African American / Q000706:statistics & numerical data*; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D015914:Estrogen Replacement Therapy / Q000379:methods*; D004967:Estrogens / Q000008:administration & dosage*; D004966:Estrogens, Conjugated (USP) / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007044:Hysterectomy; D015994:Incidence; D008875:Middle Aged; D017698:Postmenopause; D011184:Postoperative Period; D016016:Proportional Hazards Models; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology
chemical_list: D004967:Estrogens; D004966:Estrogens, Conjugated (USP)