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BREAST CANCER & HORMONE
REPLACEMENT
By Sean Henahan, Access Excellence
SEATTLE Hormone replacement therapy does not appear
to increase the risk of breast cancer in post-menopausal women, according
to the results of a large study from the Fred Hutchinson Cancer Research
Center. However, conflicting results from other studies suggest mores studies
may be needed.
At least eight million women in the United States receive estrogen replacement
therapy. The treatment is given after menopause to treat symptoms such as
hot flashes as well as to reduce or prevent osteoporosis. There is also
increasing evidence that hormone replacement therapy (HRT) can lower a woman's
risk of having a heart attack. Yet the lingering question of whether estrogen
therapy might increase the risk for breast cancer has created great uncertainty.
In the latest study, researchers studied the medical histories of 1,029
women in Washington State ranging in age from 50 to 64 years. A little more
than half of the women had developed breast cancer. Approximately 60% of
women in each group had used some form of HRT.
"In this large population based study of middle-aged women, we found
no overall association between breast cancer risk and the use of either
estrogen alone or estrogen with progestin hormone replacement regimens.
Long term use of eight years or more of the combined estrogen-progestin
HRT regimen was associated if anything, with a reduction in risk of breast
cancer. We found no association between breast cancer risk and extended
duration ( 20 years or more) of estrogen replacement therapy," commented
Dr. Janet Stanford, author of the study.
In recent years it has become more common to add a second hormone, progestin,
to HRT. While some 21% of women in each study group were receiving such
a regimen, the numbers were insufficient to determine any added benefit
or risk from such an approach, she noted:
"During the past decade the use of progestin in addition to estrogen
for HRT has increased among women in the US. However, epidemiological data
on the association between the use of combination estrogen-progestin HRT
and breast cancer are sparse. Previous studies have been limited to relatively
small numbers of exposed women and thereby have not been able to examine
specific patterns of use.
Additional studies will be needed to determine the effects of combination
hormone regimes. Studies will also be needed to determine the effects of
hysterectomy on subsequent rise for breast cancer, she said.
There is still a lack of consensus on the risks and benefits of HRT.
A recent Harvard Medical School study concluded that women aged 50 to 64
on hormone replacements for five to nine years had an increased risk of
breast cancer. Other have suggested major cardiovascular benefits in association
with HRT. Another recent study concluded that estrogen-replacement therapy
cut a woman's risk for colon cancer in half.
"More epidemiologic data on breast cancer are clearly needed. Despite
considerable scientific efforts, we know surprisingly little about the long-term
effects of combined estrogen-progestin treatment. New information should
become available because several large studies are in progress in the US
and elsewhere. For now the aggregate of the epidemiological evidence is
reassuring. We can feel a great deal of confidence that the net effect of
hormone replacement therapy with regard to length and quality of life is
beneficial," said noted breast cancer researcher Ingemaar Persson,
M.D., of the University of Uppsala, Sweden.
The complete text of Dr. Stanford's study and Dr. Persson commentary
can be found in JAMA, 7/13/95. Also look in the Newsmaker section of What's
News for an exclusive interview with Dr. Persson.
Related information at other Web sites
Oncolink's
Frequently Asked Questions about Cancer, University of Pennsylvania
Quick
Information About Cancer for Patients and Their Families, University of
Michigan
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