Menopausal Hormone Therapy (Postmenopausal Hormone Use)

In the past, many women used menopausal hormone therapy (MHT) to relieve hot flashes and other symptoms of menopause. MHT is also known as postmenopausal hormone use and hormone replacement therapy. Although MHT is approved for the short-term relief of menopausal symptoms, the U.S. Food and Drug Administration (FDA) recommends women use only the lowest dose that eases symptoms for the shortest time needed [99].  

There are two main types of MHT used today:

• Estrogen plus progestin
• Estrogen alone

Estrogen alone raises the risk of uterine cancer, so it is only used by women who no longer have a uterus (those who have had a hysterectomy). Women who still have a uterus most often use estrogen plus progestin. 

Estrogen plus progestin

Risk of breast cancer

Estrogen plus progestin increases the risk of both developing and dying from breast cancer [100-105]. When women take these hormones, their risk of having an abnormal mammogram increases within the first year of use [104,106]. And, their risk of breast cancer increases within the first five years of use [104-106].

A woman’s risk of breast cancer goes up slightly with each year a woman takes estrogen plus progestin [102]. Small yearly increases in risk can add up over time. One large study found women who use estrogen plus progestin for five or more years (and are still taking it) more than double their breast cancer risk [104].

When women stop taking MHT, their risk of breast cancer starts to decline and returns to that of a woman who has never used MHT in about five to 10 years [101,103-104,106].   

Other health risks

MHT also has a negative impact on other aspects of women's health. Results from the Women's Health Initiative, a large randomized clinical trial, showed after five years of use, estrogen plus progestin does more harm than good [103]. While using estrogen plus progestin for five years may lower the risk of colon cancer [107] and hip (and other bone) fractures [108], these benefits are outweighed by a higher risk of breast cancer and [100-113]:

• Ovarian cancer
• Heart disease
• Stroke
• Pulmonary embolism (blood clots in the lungs) 

Even short-term use (one to two years) of estrogen plus progestin can lead to an increased risk of heart disease and blood clotting problems [110]. The Women's Health Initiative data also showed taking estrogen plus progestin can increase the risk of dementia, a problem prior studies suggested might be decreased by MHT use [114-115].

Figure 2.2 below shows the absolute risks and relative risks of some health conditions with the use of estrogen plus progestin compared to placebo. 

Estrogen alone

Risk of breast cancer

Some observational studies suggest estrogen alone increases the risk of breast cancer by about 30 percent [101-102,104-105]. However, the Women's Health Initiative trial showed a decreased risk of breast cancer with estrogen alone compared to placebo after an average of six years of use [116].

The results from two large cohort studies 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 [117]. The NIH-AARP Diet and Health Study found use of estrogen alone for 10 or more years increased breast cancer risk, especially in women who were thin [118]. Researchers continue to follow the women in these studies to understand better how estrogen alone might affect breast cancer risk.

Other health risks

Beyond breast cancer, estrogen alone may impact women's health in other ways. Studies show it lowers the risk of osteoporosis and perhaps colon cancer, but raises the risk of stroke, dementia, ovarian cancer and uterine cancer [101,112-113]. Although early cohort studies suggested estrogen lowered the risk of heart disease, findings from the Women's Health Initiative showed estrogen use for up to seven years had almost no impact on risk [116]. Researchers continue to study this issue.

Recommendations for menopausal hormone therapy

If you are considering taking MHT (estrogen plus progestin or estrogen alone), discuss the risks and benefits with your health care provider.

For short-term relief of menopausal symptoms, estrogen plus progestin is an approved MHT, but the FDA recommends that it be used only at the lowest doses for the shortest time possible [99]. 

Learn about alternatives to menopausal hormone therapy for the relief of menopausal symptoms.

Updated 12/18/12

Age at First Period

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