New Warnings for Women Taking HRT.
Estrogen-Only Hormone Therapy Linked to Ovarian Cancer
July 16, 2002 -- Last week, millions of women who take a
combination form of hormone replacement therapy learned they are at increased
risk for breast cancer, heart disease, and stroke. Now comes news that women
who take estrogen alone may be at increased risk for ovarian cancer.
The new findings add to the growing body of evidence that the
dangers of long-term hormone replacement therapy (HRT) may outweigh the
benefits. Hormone therapy was originally prescribed solely to relieve the
symptoms of menopause. But over the last two decades women who no longer had
menopausal symptoms were encouraged to take HRT in the belief that it helped
prevent common diseases of aging such as heart disease and osteoporosis.
Estrogen alone is given only to women who have had
hysterectomies. The hormone progestin is added to estrogen (combination HRT)
for the treatment of women who still have their uterus, to reduce the risk of
endometrial cancer. About 38% of postmenopausal women in the U.S. use hormone
In the latest study, researchers from the National Cancer
Institute (NCI) followed 44,000 women taking estrogen only and found that these
women had a 60% higher risk of ovarian cancer than women who had never used
estrogen. Those on the hormone therapy for 20 years or more were three times as
likely to develop ovarian cancer as women who did not take it at all. Women who
took estrogen for 10 to 19 years had an 80% higher risk than nonusers.
Lead author James V. Lacey tells WebMD that this translates
into one or two additional ovarian cancers per 10,000 women taking estrogen
alone for one year.
"Our study does not prove that ... estrogen [taken by
itself] causes ovarian cancer," Lacey says. "But it is becoming more
and more obvious that hormone therapy influences many conditions that affect
women after menopause. This is a very complicated issue."
The ovarian cancer results were reported July 17 in TheJournal of the American Medical Association. In that same issue,
government researchers published the findings reported last week that prompted
health officials to halt the 16,000-subject Women's Health Initiative study
evaluating combined HRT. The risk of breast cancer rose by 26% in women on the
combined therapy for just over five years, while heart disease risk rose by 29%
and there was a 41% increase in the risk of stroke.
But the health officials did not stop the part of the study
evaluating estrogen alone in 11,000 women without uteruses because these women
did not appear to have the same increased risks for breast cancer as those on
combined therapy. The 11,000 women have been sent letters stating this, but the
issue of ovarian cancer has not been addressed.