Women under 40 who
use estrogen to ease menopause symptoms after having their ovaries
removed do not have an increased risk of breast cancer, according to a
new study.
"Their findings do provide reassurance for the
safety of taking estrogen if a woman has had her ovaries out," said Dr.
Rowan Chlebowski, a medical oncologist at the Los Angeles Biomedical
Research Institute, who was not involved in the research. For women over
45, however, the hormone therapy is linked with a 20- to 26-percent
jump in breast cancer risk.
"When
you're in your mid-40s, you want to be more careful about the use of
estrogen therapy," said Dr. Kala Visvanathan, one of the researchers on
the study.
Ovary removal,
also called oophorectomy, is thought to decrease the risk of breast and
ovarian cancer for some women. In certain cases, women at a high risk
of cancer will get the surgery for prevention, while others will have it
for reasons unrelated to cancer.
In
younger women who have not experienced menopause, having the ovaries
removed sends them into an abrupt menopause and can result in severe
symptoms, such as hot flashes. Hormone replacement therapy (HRT) remains
the most effective treatment for menopause symptoms.
But
millions of women stopped using it after a large U.S. government study
in 2002 found women taking estrogen and progestin, another hormone, had
increased risks of heart attack, stroke and breast cancer.
Another
part of the study that ended in 2004 found that women who had their
uterus removed and who were taking estrogen alone also had an increased
risk of stroke. There's been considerable discussion since then to
calculate the risks and benefits of using hormone therapy to treat
menopausal symptoms.
Visvanathan
and her colleagues wanted to see whether estrogen therapy to relieve
these symptoms would negate the benefits of having the ovaries removed.
The idea is that removing the ovaries, and the estrogen produced by
them, is responsible for the reduction in breast cancer risk.
"So
the question is, if you elect to use estrogen therapy, will you have an
increased breast cancer risk?" said Hazel Nichols, a researcher at the
National Institute of Environmental Health Sciences in the Research
Triangle Park, North Carolina, who also worked on the study.
REASSURING TO YOUNG WOMEN
The
researchers collected survey information from more than 22,000 women.
Nearly half had been diagnosed with breast cancer, while the rest of the
women hadn't.
Overall, current
estrogen users who had had both ovaries and their uterus removed had a
14-percent increase in breast cancer risk compared with women who
experienced natural menopause and never used hormones.
Women
who had the surgery done before age 40, however, had a smaller chance
of getting breast cancer, whether or not they took estrogen, the
researchers report in the medical journal Obstetrics and Gynecology.
The
risk was 24 percent lower among those on the hormone, for example, than
among women who had never had the surgery and hadn't used estrogen.
Chlebowski stated that the results apply only to women who had their ovaries
and uterus removed; women who keep their uterus would take estrogen and progesterone, which might give different results.
About
one in eight American women develop breast cancer at some point in her
life, although the majority survive, according to the American Cancer
Society.
A
24 percent reduction in that number would mean 94 out of every 100,000
women would get the cancer. Women who had the surgery before 40 but who
never used hormone therapy had an even greater drop in the risk of
breast cancer - 30 percent.
"Part
of the benefit of (the surgery) is probably being lost when a woman is
using estrogen," said Dr. Graham Colditz, a professor at Washington
University in St. Louis, who did not participate in the new research.
The
gains from the surgery are only slightly diminished by hormone therapy,
but Colditz said there is still a need for caution when using estrogen
to treat menopause symptoms. The researchers found that the risk of
breast cancer increased the older the women were at the time of surgery.
Nichols
and her colleagues found that for women who had their ovaries and
uterus removed after 50, taking estrogen was tied to a 26 percent
increase in breast cancer risk. Nichols said there's a need for more
research to help doctors best determine the risks and benefits of
hormone therapy for each woman.
"I
think what we've learned is that hormones shouldn't be prescribed to
prevent chronic disease among healthy women, but there may be a role for
them in treating severe symptoms (of menopause), and what we need to do
now is to best understand what the safest way to do that is," she told
Reuters Health.
Sources: http://in.reuters.com/article/2012/07/11/us-estrogen-ovary-idINBRE86A0V920120711
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