To use hormone replacement therapy or to not use it? That is the question. Historically, physicians recommended HRT at the time of menopause because estrogen best controlled hot flashes. Then, with further observations and data, researchers theorized that using estrogen might also decrease a women's risk of cardiac disease, osteoporosis, Alzheimer's disease and other chronic diseases. The benefits of HRT appeared numerous, yet comprehensive scientific investigations of this treatment approach were not available. Therefore, questions remained about the possible risks of HRT such as an increased risk of developing diseases like breast cancer.
An "about face" on the use of HRT at the time of menopause occurred following the release of information from a study called the Women's Health Initiative (which concluded in 2002). This comprehensive study found that HRT provided women with no significant protection from developing cardiac disease. Instead, the study found a possible increased risk of heart attacks and stroke for women using this therapy. Additional data also suggested that different risks occurred if a woman used combination estrogen and progesterone therapy versus estrogen alone. For example, the increased risk of having a stroke was not seen in women aged 50 to 59 years if they were receiving estrogen only treatment (rather than estrogen and progesterone therapy).
These conflicting findings add confusion to the decision on whether to use HRT. On the one hand, this therapy clearly helps with hot flashes and osteoporosis. But now, there is also concern about increasing a women's risk of heart disease and stroke.
Since the Women's Health Initiative, additional studies have been performed. While there are still lots of questions and uncertainties, these more recent studies are trying to reconcile the different information about the relationship between HRT and heart disease. One current theory is that estrogen replacement early on in the menopausal transition may delay early atherosclerosis (thickening of the arteries), whereas estrogen started later in menopause may actually trigger a coronary event (i.e. heart attack) if thickening of the arteries has already begun. In contrast, the frequency of stroke remains higher if a women uses HRT whether or not it was started early or late in menopause.
The possible increased risk of breast cancer remains a controversial concern. Review of the available data suggests that the use of combination HRT for the first 5 years after menopause does not increase a women's risk of breast cancer. However, there appears to be an increased risk (8 per 10,000 women per year) of breast cancer after 5 years of combination HRT. For women receiving estrogen-only HRT, the increased risk of breast cancer is lower.
All of the studies continue to show that estrogen is protective against osteoporosis. Please see our later discussion about post-menopausal osteoporosis for more information about this topic.
Estrogen remains an excellent treatment for hot flashes, but there are many uncertainties and risks that one must consider. At this point, HRT should not be used in older women who are already several years into menopause. HRT can be used for women for roughly the first five years out from menopause as long as these women have no cardiac risk, and no history of stroke or breast cancer. Beyond these guidelines, there needs to be a careful weighing of the individuals risks and benefits of HRT by a woman and her primary care provider.