title: Association of mammographic density with the pathology of subsequent breast cancer among postmenopausal women.
abstract: BACKGROUND
  Limited studies have examined the associations between mammographic density and subsequent breast tumor characteristics.
  
  
  METHODS
  Eligible women were part of a case-control study of postmenopausal breast cancer, were 40 years or older and had a routine mammogram 4 years or more before their diagnosis. Mammographic density (percent density, dense area, and nondense area) was estimated using a computer-assisted thresholding program. At the time of cancer diagnosis, cases were classified as asymptomatic or symptomatic based on medical record review and breast imaging workup. Pathologic review was done blinded to the density status. Linear regression models and tests for trend examined the association between pathologic characteristics of the breast tumor and the components of density for all participants, and stratified by symptom status at diagnosis.
  
  
  RESULTS
  Of the 286 eligible cases, 77% were 60 years or older and mean percent density was 29.5% (SD, 14.6%). Density was not significantly associated with tumor size (P = 0.22), histologic type (P = 0.77), estrogen receptor (P = 0.11) or progesterone receptor (P = 0.37) status, mitotic activity (P = 0.12), or nuclear pleomorphism (P = 0.09; P values for percent density). An inverse association was suggested between tumor grade and percent density (32.0%, 30.3%, 26.7% for grades 1-3; P = 0.06 for trend). The inverse association with tumor grade and its components (nuclear pleomorphism and tubular differentiation) was only evident among the 97 symptomatic women; positive associations of estrogen receptor (P = 0.009) and progesterone receptor (P = 0.04) were also seen with percent density only in this subgroup.
  
  
  CONCLUSIONS
  The inverse association between tumor grade and percent density in the symptomatic population could inform the biology of the association between mammographic density and breast cancer risk.
authors.affiliation: Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
authors.forename: Karthik
authors.initials: K
authors.lastname: Ghosh
authors.forename: Kathleen R
authors.initials: KR
authors.lastname: Brandt
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Sellers
authors.forename: Carol
authors.initials: C
authors.lastname: Reynolds
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Scott
authors.forename: Shaun D
authors.initials: SD
authors.lastname: Maloney
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Carston
authors.forename: V Shane
authors.initials: VS
authors.lastname: Pankratz
authors.forename: Celine M
authors.initials: CM
authors.lastname: Vachon
mesh_terms: D000328:Adult; D000368:Aged; D001940:Breast / Q000033:anatomy & histology*; D001943:Breast Neoplasms / Q000145:classification / Q000175:diagnosis / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008327:Mammography; D008499:Medical Records; D008875:Middle Aged; D017698:Postmenopause