title: Circulating sex hormones and mammographic breast density among postmenopausal women.
abstract: The use of breast density as an intermediate or predictive marker of breast cancer risk is limited by an incomplete understanding of the etiology of breast density. High blood levels of endogenous estrogens and androgens are associated with increased risk of breast cancer among postmenopausal women. We sought to examine whether these hormones are also associated with breast density. The Wisconsin Breast Density Study enrolled 257 postmenopausal women, ages 55-70 years, with no history of postmenopausal hormone use, from mammography clinics in Madison, Wisconsin. Subjects provided a blood sample for sex hormone analysis, and breast density was measured from subjects' screening mammograms using a computer-assisted thresholding method. Numerous sex hormones were associated with breast density in age-adjusted analyses. However, further adjustment for body mass index and other potentially confounding factors substantially attenuated or eliminated these associations. In the fully adjusted model, there remained a positive association between percent breast density and serum progesterone (P=0.03), with percent density rising from 11.9% (95% CI: 9.8, 14.1%) among women in the lowest quartile of serum progesterone to 15.4% (12.9, 18.2%) among women in the highest quartile. There was also a positive association between sex hormone binding globulin and percent breast density (P=0.06). In contrast, there were no independent associations between percent breast density and estradiol (total, free, or bioavailable), estrone, estrone sulfate, or testosterone (total, free, or bioavailable). These results suggest that breast density has a hormonal etiology; however, it may differ in important ways from that of breast cancer risk.
authors.affiliation: Department of Surgery, University of Vermont, 1 S. Prospect St, Rm 4428B, Burlington, VT 05401, USA. Brian.Sprague@uvm.edu
authors.forename: Brian L
authors.initials: BL
authors.lastname: Sprague
authors.forename: Amy
authors.initials: A
authors.lastname: Trentham-Dietz
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Gangnon
authors.forename: Diana S M
authors.initials: DS
authors.lastname: Buist
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Burnside
authors.forename: Erin J Aiello
authors.initials: EJ
authors.lastname: Bowles
authors.forename: Frank Z
authors.initials: FZ
authors.lastname: Stanczyk
authors.forename: Gale S
authors.initials: GS
authors.lastname: Sisney
mesh_terms: D000368:Aged; D001940:Breast / Q000473:pathology*; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood*; D011863:Radioimmunoassay
chemical_list: D012739:Gonadal Steroid Hormones