title: Endogenous sex hormones and breast density in young women.
abstract: BACKGROUND
  Breast density is a strong risk factor for breast cancer and reflects epithelial and stromal content. Breast tissue is particularly sensitive to hormonal stimuli before it fully differentiates following the first full-term pregnancy. Few studies have examined associations between sex hormones and breast density among young women.
  
  
  METHODS
  We conducted a cross-sectional study among 180 women ages 25 to 29 years old who participated in the Dietary Intervention Study in Children 2006 Follow-up Study. Eighty-five percent of participants attended a clinic visit during their luteal phase of menstrual cycle. Magnetic resonance imaging measured the percentage of dense breast volume (%DBV), absolute dense breast volume (ADBV), and absolute nondense breast volume (ANDBV). Multiple-linear mixed-effect regression models were used to evaluate the association of sex hormones and sex hormone-binding globulin (SHBG) with %DBV, ADBV, and ANDBV.
  
  
  RESULTS
  Testosterone was significantly positively associated with %DBV and ADBV. The multivariable geometric mean of %DBV and ADBV across testosterone quartiles increased from 16.5% to 20.3% and from 68.6 to 82.3 cm(3), respectively (Ptrend ≤ 0.03). There was no association of %DBV or ADBV with estrogens, progesterone, non-SHBG-bound testosterone, or SHBG (Ptrend ≥ 0.27). Neither sex hormones nor SHBG was associated with ANDBV except progesterone; however, the progesterone result was nonsignificant in analysis restricted to women in the luteal phase.
  
  
  CONCLUSIONS
  These findings suggest a modest positive association between testosterone and breast density in young women.
  
  
  CONCLUSIONS
  Hormonal influences at critical periods may contribute to morphologic differences in the breast associated with breast cancer risk later in life.
authors.affiliation: University of Maryland School of Medicine, Baltimore, Maryland.
authors.forename: Seungyoun
authors.initials: S
authors.lastname: Jung
authors.affiliation: University of Southern California Keck School of Medicine, Los Angeles, California.
authors.forename: Frank Z
authors.initials: FZ
authors.lastname: Stanczyk
authors.affiliation: Fox Chase Cancer Center, Philadelphia, Pennsylvania.
authors.forename: Brian L
authors.initials: BL
authors.lastname: Egleston
authors.affiliation: University of Iowa, Iowa City, Iowa.
authors.forename: Linda G
authors.initials: LG
authors.lastname: Snetselaar
authors.affiliation: Kaiser Permanente Center for Health Research, Portland, Oregon.
authors.forename: Victor J
authors.initials: VJ
authors.lastname: Stevens
authors.affiliation: University of California San Francisco, San Francisco, California.
authors.forename: John A
authors.initials: JA
authors.lastname: Shepherd
authors.affiliation: Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
authors.forename: Linda
authors.initials: L
authors.lastname: Van Horn
authors.affiliation: Kaiser Permanente Center for Health Research, Portland, Oregon.
authors.forename: Erin S
authors.initials: ES
authors.lastname: LeBlanc
authors.affiliation: Louisiana State University School of Medicine, New Orleans, Louisiana.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Paris
authors.affiliation: Dangeard Group, San Francisco, California.
authors.forename: Catherine
authors.initials: C
authors.lastname: Klifa
authors.affiliation: University of Maryland School of Medicine, Baltimore, Maryland. jdorgan@som.umaryland.edu.
authors.forename: Joanne F
authors.initials: JF
authors.lastname: Dorgan
mesh_terms: D000328:Adult; D001940:Breast / Q000033:anatomy & histology*; D001943:Breast Neoplasms / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D004958:Estradiol / Q000097:blood*; D004967:Estrogens / Q000097:blood*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D012307:Risk Factors; D013739:Testosterone / Q000097:blood*
chemical_list: D004967:Estrogens; D013739:Testosterone; D004958:Estradiol