Estrogen-Progestin: Too Risky?
Q. I have a family history of osteoporosis, so my gynecologist has been urging me to go on hormone replacement therapy. I've been resisting because I'm worried about breast cancer. Last week, I heard that a new study found the estrogen-progestin combination can also increase a woman's risk of breast cancer. What's your recommendation now?
The study you refer to (published in the January 26, 2000, issue of the Journal of the American Medical Association) found that women who take menopausal hormone replacement therapy (HRT) that includes estrogen and progestin have a higher risk of breast cancer than those who take estrogen alone. The two hormones are usually prescribed together for women who have not had hysterectomies -- when taken alone, estrogen increases the risk of uterine (endometrial) cancer between five and 14 times. Adding progestin reduces the uterine cancer risk to what it would be if you weren't taking any hormones at all. (A woman who has had a hysterectomy no longer has her uterus and doesn't need to take progestin.)
The new study, by researchers from the National Cancer Institute, followed 46,355 postmenopausal women from 1980 to 1995. They found that "lean" women who took the estrogen-progestin combo had an 8 percent increase in breast cancer risk with each year of use -- compared to a 1 percent increase among those who took estrogen alone. (Researchers aren't sure why, but the study found no increased risk among heavy women.)
This study gives us important new information about the risks of HRT, but it won't be the last word on the subject. In the meantime, women with a strong family history of breast cancer will probably be advised against taking HRT. However, they, and the vast majority of women who have chosen not to take HRT, can still do a lot to protect themselves from both osteoporosis and heart disease by making dietary changes and exercising regularly.
You should also know that the risk of breast cancer is not eliminated if you don't take hormones. Catherine Schairer, Ph.D., the NCI epidemiologist who directed the study, told the New York Times that among any group of 100,000 women (of normal weight, aged 60 to 64) who do not take any hormones, about 350 would be expected to develop breast cancer over a five-year period. If all were on HRT, 560 cases of breast cancer would be expected over the same period.
Hormone replacement is prescribed for the following reasons:
To relieve hot flashes, vaginal dryness, and other menopausal symptoms.
To protect against bone loss that can lead to osteoporosis and vertebral and hip fractures.
To protect against coronary heart disease.
Some evidence also suggests that HRT may protect against Alzheimer's Disease, colon cancer, and macular degeneration, a major age-related cause of blindness.
Taking hormone replacement has always been a calculated risk for women. While the results of this study are bad news for those who want and need the benefits of hormone replacement, it shouldn't entirely rule out HRT for those at high risk for osteoporosis and heart disease -- both are far more common than breast cancer. Heart disease, not breast cancer, is the leading killer of women.