Many women have used postmenopausal hormones to relieve menopausal symptoms and to reduce the risk of some chronic diseases, such as heart disease and osteoporosis. There is now a great deal of evidence that postmenopausal hormone therapy should not be used to prevent chronic disease. For short-term relief of menopausal symptoms, postmenopausal hormones are approved therapies, but the Food and Drug Administration (FDA) recommends that they be used only at the lowest doses for the shortest possible time necessary [80].

There are two main types of postmenopausal hormones used today: estrogen alone and estrogen plus progestin. Since estrogen alone raises the risk of uterine cancer, it is only used by women who no longer have a uterus (those who have had a hysterectomy). Estrogen plus progestin is the therapy used most often by women who still have a uterus.

Estrogen plus progestin

Estrogen plus progestin increases the risk of both developing and dying from breast cancer [81-88]. When women take these hormones, their risk of having an abnormal mammogram increases the first year of use [87,88]. Their risk of getting breast cancer starts to rise within the first five years of use [87,88]. For each year that a woman takes estrogen plus progestin, her risk of breast cancer goes up slightly [85].

Small yearly increases in risk can add up over time. One large study found that women who use estrogen plus progestin for five or more years (and are still taking it) more than double their breast cancer risk [87]. When women stop taking these hormones, their risk of breast cancer starts to decline almost right away and returns to that of a woman who has never used hormones in about five to 10 years [82,86,89].

Postmenopausal hormones also have a negative impact on other aspects of women's health. Results from the Women's Health Initiative a large randomized clinical trial) showed that after five years of use, estrogen plus progestin does more harm than good [86]. While using estrogen plus progestin for five years may lower the risk of colon cancer [90] and osteoporosis [91], these benefits are outweighed by a higher risk of breast cancer [90], ovarian cancer [92], heart disease [93], stroke [94] and pulmonary embolism (blood clots in the lungs) [93]. Even short-term use of only one to two years can lead to increases in the risk of heart disease and blood clotting problems [93]. Figure 2.2 below shows the absolute and relative risks for some of these conditions.

Studies also show that hormone use does little to increase women's quality of life in their postmenopausal years, even in those who have hot flashes. These results call into question one of the main reasons many women choose to take hormones—to simply feel better [95,96]. Moreover, the Women's Health Initiative data show that taking estrogen plus progestin can increase the risk of dementia, a problem that earlier studies suggested might be decreased by hormone use [97-99].

Estrogen alone

Although observational studies suggest that estrogen alone raised the risk of breast cancer about 30 percent [81-85,87], the Women's Health Initiative trial showed no increased risk of breast cancer with estrogen alone compared to placebo with an average follow-up of 7.1 years [100]. However, results from two large cohort studies have raise the question of the safety of longer-term use of estrogen alone. As in the Women's Health Initiative, the Nurses Health Study found no increased risk of breast cancer among women who used estrogen alone for less than 10 years. But, there was an increase in risk of breast cancer after 20 years of use [101]. Similar to these findings, a recent cohort study found that use of estrogen alone for 10 or more years increased breast cancer risk, especially in women who were thin [102]. Researchers continue to follow the women in this study to better understand how estrogen alone might affect cancer risk.

Beyond breast cancer, estrogen alone may also impact women's health in other ways. Studies show that it can lower the risk of osteoporosis and perhaps colon cancer, but raise the risk of stroke, dementia, ovarian cancer and uterine cancer [82,103,104]. Although prior cohort studies suggested that estrogen can lower the risk of heart disease, findings from the Women's Health Initiative showed that estrogen use for up to seven years had almost no impact on risk [105]. Researchers continue to study this issue.

Recommendations for postmenopausal hormone use

In deciding whether or not to take postmenopausal hormones, you should discuss the risks and benefits with your health care provider. For most women, postmenopausal hormones, especially estrogen plus progestin, should not be taken to prevent chronic disease. The risks simply outweigh the benefits. There are safer ways to prevent disease and improve your health. For example, there are other drugs to help reduce your risk of osteoporosis. For short-term relief of menopausal symptoms, postmenopausal hormones are approved therapies, but the Food and Drug Administration (FDA) recommends that they be used only at the lowest doses for the shortest possible time necessary [80].

Discussing these issues with your health care provider will help you decide if, and for how long, to use postmenopausal hormones.

Updated 11/09/09

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