title: Effects of hormone replacement therapy regimens on mammographic breast density: the role of progestins.
abstract: OBJECTIVE
  To evaluate the effects of different regimens of hormone replacement therapy (HRT) on mammographic breast density.
  
  
  METHODS
  Mammograms of 113 healthy postmenopausal women who were on different HRT regimens were evaluated retrospectively. All women had a baseline mammography and at least one mammogram after at least 12 months of HRT. Four parenchymal patterns were considered mammographically. Quantification of density changes that occurred on follow-up mammograms was done qualitatively and with reference to densities on baseline mammograms.
  
  
  RESULTS
  Sixty women were treated with a continuous estrogen-progestin combination; 16 with a cyclic estrogen-progestin combination and 37 were with estrogen only. Twenty-six women had increased mammographic density after HRT. Mammographic density increase was detected in 23 women (38.3%) of the continuous estrogen-progestin combination group, two women (12.5%) of the cyclic estrogen-progestin combination group and one woman (2.7%) of the estrogen-only group. Mammographic density increase was more common among women in the continuous estrogen-progestin combination group than the other groups and this difference was found to be statistically significant (P < 0.001). Breast density increase was observed in 18 of 30 women (60%) with higher doses of progestin compared to 5 of 30 women (16.7%) with lower dose (P < 0.05).
  
  
  CONCLUSIONS
  Postmenopausal HRT may increase mammographic breast density. Breast density appears to be mostly affected by higher doses and continuous administration of progestin.
authors.affiliation: Department of Radiology, Faculty of Medicine, Uludag University, Bursa, Turkey.
authors.forename: Naile Bolca
authors.initials: NB
authors.lastname: Topal
authors.forename: Serdal
authors.initials: S
authors.lastname: Ayhan
authors.forename: Ugur
authors.initials: U
authors.lastname: Topal
authors.forename: Tufan
authors.initials: T
authors.lastname: Bilgin
mesh_terms: D001940:Breast / Q000187:drug effects* / Q000473:pathology*; D001943:Breast Neoplasms / Q000139:chemically induced / Q000473:pathology; D004967:Estrogens / Q000008:administration & dosage; D005260:Female; D020249:Hormone Replacement Therapy / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D011372:Progestins / Q000008:administration & dosage; D012189:Retrospective Studies
chemical_list: D004967:Estrogens; D011372:Progestins