title: Mammographic breast density response to aromatase inhibition.
abstract: OBJECTIVE
  Mammographic breast density (MBD) is decreased by tamoxifen, but the effect of aromatase inhibitors is less clear.
  
  
  METHODS
  We enrolled early-stage postmenopausal patients with breast cancer initiating adjuvant aromatase inhibitor therapy and ascertained mammograms before and at an average 10 months of aromatase inhibitor therapy. We matched cases to healthy postmenopausal women (controls) from a large mammography screening cohort on age, baseline body mass index, baseline MBD, and interval between mammograms. We estimated change in MBD using a computer-assisted thresholding program (Cumulus) and compared differences between cases and matched controls.
  
  
  RESULTS
  In predominantly White women (96%), we found 14% of the 387 eligible cases had a MBD reduction of at least 5% after an average of 10 months of aromatase inhibitor therapy. MBD reductions were associated with higher baseline MBD, aromatase inhibitor use for more than 12 months, and prior postmenopausal hormone use. Comparing each case with her matched control, there was no evidence of an association of change in MBD with aromatase inhibitor therapy [median case-control difference among 369 pairs was -0.1% (10th and 90th percentile: -5.9%, 5.2%) P = 0.51]. Case-control differences were similar by type of aromatase inhibitor (P's 0.41 and 0.56); prior use of postmenopausal hormones (P = 0.85); baseline MBD (P = 0.55); and length of aromatase inhibitor therapy (P = 0.08).
  
  
  CONCLUSIONS
  In postmenopausal women treated with aromatase inhibitors, 14% of cases had a MBD reduction of more than 5%, but these decreases did not differ from matched controls. These data suggest that MBD is not a clinically useful biomarker for predicting the value of aromatase inhibitor therapy in White postmenopausal women.
authors.affiliation: Department of Health Sciences, Mayo Clinic College of Medicine, Rochester, Minnesota, 55905, USA. vachon.celine@mayo.edu
authors.forename: Celine M
authors.initials: CM
authors.lastname: Vachon
authors.forename: Vera J
authors.initials: VJ
authors.lastname: Suman
authors.forename: Kathleen R
authors.initials: KR
authors.lastname: Brandt
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Kosel
authors.forename: Aman U
authors.initials: AU
authors.lastname: Buzdar
authors.forename: Janet E
authors.initials: JE
authors.lastname: Olson
authors.forename: Fang-Fang
authors.initials: FF
authors.lastname: Wu
authors.forename: Lynn M
authors.initials: LM
authors.lastname: Flickinger
authors.forename: Giske
authors.initials: G
authors.lastname: Ursin
authors.forename: Catherine R
authors.initials: CR
authors.lastname: Elliott
authors.forename: Lois
authors.initials: L
authors.lastname: Shepherd
authors.forename: Richard M
authors.initials: RM
authors.lastname: Weinshilboum
authors.forename: Paul E
authors.initials: PE
authors.lastname: Goss
authors.forename: James N
authors.initials: JN
authors.lastname: Ingle
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D047072:Aromatase Inhibitors / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D016022:Case-Control Studies; D017024:Chemotherapy, Adjuvant; D005260:Female; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D017698:Postmenopause; D016387:Women's Health / Q000706:statistics & numerical data
chemical_list: D047072:Aromatase Inhibitors