Frequently Asked Questions ^{< back}

What is hormone replacement therapy?

Hormone Replacement Therapy (HRT) provides women with the female hormones that decrease as they age. When the hormone estrogen is given alone, it is usually referred to as "ERT." When the hormone progestin is combined with estrogen, it is generally called "HRT." Estrogen is a female hormone that brings about changes in other organs in the body. Progesterone is a female hormone that prepares the uterus for a pregnancy each month. During the transition to menopause ("perimenopause") these hormone levels start to fluctuate, causing some uncomfortable symptoms. When the ovaries stop producing estrogen and progesterone, menstrual periods cease and the woman has experienced menopause.

What are the benefits of HRT?

HRT has been used to relieve the short-term symptoms of menopause, such as hot flashes, sweats, and disturbed sleep. It is also believed to be useful in preventing or alleviating an increased rate of bone loss that leads to osteoporosis. Preliminary evidence shows that HRT may be helpful in preventing Alzheimer's disease, colon cancer, and macular degeneration (age-related vision loss). HRT is very valuable in the prevention and treatment of osteoporosis as well, a condition responsible for over 1,500,000 pathologic fractures annually in the US.

What are the risks of HRT?

Short-term side effects: Some women report side effects from taking HRT, including unusual vaginal discharge and bleeding, headaches, nausea, fluid retention and swollen breasts. Some women think HRT will make them gain weight while taking HRT, but research now shows this is not true. Some women do gain weight during menopause, but it is because their metabolism slows down as they age, and they many not be increasing their amount or level of physical activity. Short-term benefits or side effects should become apparent within weeks or months after treatment begins.

Long-term risks (These will not be readily apparent for each individual woman):

Cancer: There is concern that HRT can increase the risk of some cancers. When estrogen is taken alone, it raises the risk of endometrial cancer (lining of the uterus). Adding progestin with estrogen (HRT) can dramatically reduce this risk. Progestin is added to prevent the overgrowth (or hyperplasia) of cells in the lining of the uterus, so women who still have an intact uterus are generally given this combined therapy.

Breast Density: Taking both estrogen and progestin also can affect a woman's breast density. Increased breast density from HRT makes it more difficult for a radiologist to read some mammograms, leading to the need for follow-up mammograms or breast biopsies. Increased density also is a concern because other studies have shown that women age 45 and older whose mammograms show at least 75 percent dense tissue are at increased risk for breast cancer. However, it is not known if increased breast density due to HRT carries the same risk for breast cancer as having naturally dense breasts. Data from the Postmenopausal Estrogen / Progestin Interventions (PEPI) trial at NCI indicate that about 25 percent of women who use combined HRT have an increase in breast density on their mammograms, compared to about 8 percent of women taking estrogen alone. One study showed that stopping HRT for about 2 weeks before having a mammogram improved the readability of the mammogram. However, further research is needed to confirm the usefulness of this approach.

Why is menopausal hormone replacement therapy used in spite of a possible cancer risk?

The known benefits of HRT can improve the quality of life for many women, by reducing uncomfortable hot flashes, night sweats, and vaginal dryness. There also is evidence that HRT helps prevent and treats osteoporosis, and preliminary evidence that it can help prevent other problems associated with age, including Alzheimer's disease, colon cancer and deterioration of eyesight. The addition of progestin to the treatment has dramatically reduced the risk of endometrial cancer. Until the questions about the risk of breast cancer are more fully answered, many women and their health care providers believe the benefits outweigh the risks. However, women considered to be at high risk for breast cancer, or who have other concerns about the risks, might want to use alternative methods to alleviate menopausal symptoms. Family history of breast cancer, early age of the first menstrual period (menarche), late age of child bearing, high fat diet, obesity, increased breast density on mammograms, and certain benign breast lesions increase the underlying risk of developing a breast cancer. These factors need to be considered when deciding to take HRT. A woman also might consider any family history of osteoporosis or heart disease when making a decision about HRT.

What additional studies shed light on the benefits of hormone replacement therapy?

A very large study in Denmark followed almost 700,000 women for about 6 years and discovered an astonishing finding: women who use non oral estrogen (applied to skin or under the skin) had a decrease risk for cardiovascular disease by almost 40% compared to women who took oral estrogen or to those WHO TOOK NO ESTROGEN. A re-evaluation of the Women's Health Initiative showed that while there was a very subtle increase in breast cancer risk in this study, it occurred only among women taking oral synthetic estrogen who began that therapy long after the onset of menopause. In fact women who began this same therapy at or near the time of menopause, actually saw about a 24% reduction I breast cancer risk.

Are there other drug therapies known to treat conditions related to menopause?

A class of drugs called SSRIs (such as Prozac and Zoloft) is very effective in treating menopause-related symptoms of depression or mood changes. Vitamin E and Clonidine, a drug typically used for high blood pressure, can alleviate hot flashes. To prevent osteoporosis, bisphosphonates, alendronate, raloxifene and calcitonin are used in women who are at high risk for bone loss. No alternatives to estrogen exist for prevention of Alzheimer's disease, colon cancer, and macular degeneration - diseases for which preliminary evidence suggests HRT is beneficial. Testosterone is a valuable addition to hormone replacement therapy for many women. It can help prevent and treat osteoporosis, improve exercise function and mental clarity and often improve sexual desire.

Who should not use HRT?

HRT is often not recommended for women who have any of the following conditions:
Vaginal bleeding of an unknown cause;
Suspected breast cancer or history of breast cancer;
History of endometrial cancer or cancer of the uterus;
Chronic disease of the liver; or
History of venous thrombosis (blood clots in the veins or legs, or in the lung). This includes women who have had thrombosis or blood clots during pregnancy or when taking birth control pills. Although the risk of blood clots in women is very low, HRT increases the risk.