Estrogen is one of the natural hormones produced by the ovaries. As women age, ovarian function decreases and hormone production slows. As a result, women may experience hot flashes, insomnia and a variety of other changes in their normal physical function.
There is a great deal of debate on whether or not estrogen should be replaced as women go through menopause. Dr. Trudy Bush, at the Johns Hopkins School of Hygiene and Public Health, is an expert in research on hormone replacement. She says some members of the medical community feel estrogen supplements put women at risk of breast and uterine cancer, while others say evidence is weak and the replacements improve the quality of women's lives as they get older.
Q: What are hormones?
A: They are powerful substances found in the tissues of women's reproductive organs. They also circulate through the blood to act on tissues in other parts of the body. Research shows that there is estrogen in tissues in virtually every part of a woman's body, including the skin, brain, heart, bladder and vagina.
Q: What does that mean for a woman as she gets closer to menopause?
A: Since estrogen is present in these tissues throughout a woman's adult life, there will be physical changes as the ovaries slow down and estrogen levels drop. There is a connection between the parts of the body mentioned above and the symptoms of menopause. They include hot flashes and flushes, moodiness, incontinence and painful intercourse from diminished lubrication.
Q: What does estrogen replacement do?
A: It alleviates the symptoms of menopause and prevents osteoporosis, which is one of the characteristics of estrogen loss. But the dose of estrogen in replacement is only about one-third of the amount produced naturally by ovaries.
Q: When should women begin hormone replacement therapy?
A: Generally, if the symptoms of menopause are severe, hormone replacement is warranted. For some women, that could be their early 40s. For others, it is not until they have their last periods.
Q: What does it involve?
A: For most women, the replacement is a pill once a day. If the uterus has not been removed, the hormones estrogen and progestin are both given. Scientists estimate that 10 percent to 15 percent of women going through menopause are on hormone replacement therapy.
Q: What are the risks?
A: Estrogen has been shown to cause uterine cancer in some women, but when progestins are added, that risk virtually is eliminated. In some limited instances, researchers feel there may be a link between estrogen and breast cancer. But hormone replacement therapy uses a natural substance, much like insulin. We've been using hormone therapy for at least 50 years and a general risk of breast cancer hasn't shown up yet. And we've known for 25 years that adding progestin eliminates the risk of uterine cancer.
Q: Why are some women reluctant to have hormone replacement?
A: The use of replacement therapy over long periods of time has not had detailed trials to assess its safety and ability to prevent osteoporosis and heart disease. However, we do have good evidence that losing estrogen puts women at risk of those diseases and others. So women need to feel they are empowered to make informed decisions about whether they want to be protected from those diseases and add quality to their lives, or whether they can adjust to the physical changes of menopause if even small risks make them uncomfortable.
Q: Who shouldn't have it?
A: Women who have a history of blood clots associated with estrogen should not have replacement therapy. Also, women who have breast cancer or gynecologic cancers should not have it. However, there is some support in the medical community for giving estrogen to women who have had breast cancer if they have severe symptoms of menopause. Women with a family history of breast cancer need to have a frank discussion with their physicians about their individual risks.
Q: Are there side effects?
A: Some women experience breast tenderness and nausea, but those symptoms generally disappear in three to six months. One-third to one-half of women who still have their uteruses resume their menstrual periods. To counteract symptoms, doctors currently recommend a pill every day, rather than 25 days of the month as originally prescribed. An alternative is a patch applied to the stomach or buttocks every three and a half days. There also are vaginal creams that relieve sexual discomfort and may even be effective in relieving some stress incontinence.
Q: How often should a woman see her physician if she is on hormone replacement therapy?
A: She should have a baseline examination and mammogram since estrogen will change breast tissue. After that, she should receive annual checkups and mammograms, as should all women in this age group.
Dr. Matanoski is a physician and professor of epidemiology at the Johns Hopkins School of Public Health.