Neutral effect of ultra-low-dose continuous combined estradiol and norethisterone acetate on mammographic breast density.
OBJECTIVE
To compare the effects of two different ultra-low doses of continuous combined hormone therapy and placebo on mammographic breast density in postmenopausal women.


METHODS
A subpopulation of 255 postmenopausal women from the CHOICE trial were randomly assigned to 0.5 mg 17beta-estradiol (E2) + 0.25 mg norethisterone acetate (NETA), 0.5 mg E2 + 0.1 mg NETA, or placebo. Women using hormone replacement therapy (HRT) up to 2 months prior to the study were excluded; 154 women fulfilled the inclusion criteria. Mammograms were performed at baseline and after 6 months. Breast density was evaluated by visual classification scales and a computer-assisted digitized technique.


RESULTS
No significant differences were detected between the active treatment groups and the placebo group in the digitized quantification. The mean baseline values for density around 20% were unchanged after 6 months. Also, visual classifications showed no increase in breast density in any study group.


CONCLUSIONS
In contrast to currently available bleed-free regimens, the new ultra-low-dose combination of 0.5 mg E2 and 0.1 mg NETA seems to have very little or even a neutral effect on the breast. Both digitized quantification and visual assessment of breast density were unchanged after 6 months. Larger prospective studies should be performed to confirm this new finding.
Lundström
E
E
Department of Obstetrics, Karolinska University Hospital, Stockhom, Sweden.
Bygdeson
M
M
Svane
G
G
Azavedo
E
E
von Schoultz
B
B
D000328:Adult; D000368:Aged; D001940:Breast / Q000187:drug effects* / Q000473:pathology; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D009640:Norethindrone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D000077563:Norethindrone Acetate; D017698:Postmenopause; D013548:Sweden; D016896:Treatment Outcome
D004958:Estradiol; D000077563:Norethindrone Acetate; D009640:Norethindrone