How does menopausal hormone replacement therapy (HRT) affect breast density?

Updated: Sep 13, 2021
  • Author: Nicole K Banks, MD; Chief Editor: Richard Scott Lucidi, MD, FACOG  more...
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Mammographic density increases in about 25% of women who use either cyclical or continuous combined HT, as evidenced in a randomized placebo-controlled study. [13] The degree of density increase is 5%. Unopposed estrogen and tibolone have no significant effect.

Results of the Million Women Study contrasted with evidence from placebo-controlled studies, showing that both unopposed and combined HT increased density. Other observational evidence suggested that the cessation of HT for a few weeks before mammography may improve accuracy of the imaging study.

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