How does menopausal hormone replacement therapy (HRT) affect endometrial cancer risk?

Updated: Sep 13, 2021
  • Author: Nicole K Banks, MD; Chief Editor: Richard Scott Lucidi, MD, FACOG  more...
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In 1975, Zeil and Finle proved the relationship between the administration of exogenous estrogens and an increased incidence of endometrial cancer. [2] More recently, evidence from randomized controlled studies showed a definite association between HT and uterine hyperplasia and cancer. HT based on unopposed estrogen is associated with this observed risk, which is unlike the increased risk of breast cancer linked with combined rather than unopposed HT.

Continuous combined regimens have not been associated with an increased risk. [15] However, cyclical regimens—even ones involving 10-14 days of progestogens per month—do increase the risk after 5 years of usage.

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