How does a history of menopausal hormone replacement therapy (HRT) affect breast cancer survival rates?

Updated: Sep 24, 2019
  • Author: Nicole K Banks, MD; Chief Editor: Richard Scott Lucidi, MD, FACOG  more...
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Answer

Answer

Survival of patients with breast cancer who are receiving HT is difficult to measure reliably. Overall, observational data suggest that HT has no significant effect on survival compared with no HT.

Obesity exerts a modifying effect on the association between hormone use and breast cancer. The risk of breast cancer increases in association with hormone use for lean women but not for heavy women. Adipose tissue is the primary source of endogenous estrogen after menopause, and circulating levels of estrogen are considerably elevated in obese postmenopausal women. Therefore, exogenous estrogen may have less of an effect on estrogen availability in heavy women than in lean women.

A study published in the New England Journal of Medicine revealed a sharp decline in the rate of new cases of breast cancer in 2003 in the United States. [14] This change may have been related to a national decline in the use of HT. The decrease occurred only in women older than 50 years and was more evident in women with cancers that were estrogen-receptor positive, ie, tumors that need estrogen to grow and multiply. Because the analysis was based on population statistics, the finding did not prove a link between HT and the incidence of breast cancer. This link can be proven only with randomized controlled trials.


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