THURSDAY, March 14 ( HealthDay News) -- Although several large
studies in recent years have linked the use of hormone therapy
after menopause with an increased risk of breast cancer, the
authors of a new analysis claim the evidence is too limited to
confirm the connection.
Dr. Samuel Shapiro, of the University of Cape Town Medical
School in South Africa, and his colleagues took another look at
three large studies that investigated hormone therapy and its
possible health risks -- the Collaborative Reanalysis, the Women's
Health Initiative (WHI) and the Million Women Study.
Together, the results of these studies found overall an
increased risk of breast cancer among women who used the
combination form of hormone therapy with both estrogen and
progesterone. Women who have had a hysterectomy and use
estrogen-only therapy also have an increased risk, two of the
studies found. The WHI, however, found that estrogen-only therapy
may not increase breast cancer risk and may actually decrease it,
although that has not been confirmed in other research.
After the WHI study was published in July 2002, women dropped
hormone therapy in droves. Many experts pointed to that decline in
hormone therapy use as the reason breast cancer rates were
Not so, Shapiro said: "The decline in breast cancer incidence
started three years before the fall in HRT use commenced, lasted
for only one year after the HRT drop commenced, and then
For instance, he said, between 2002 and 2003, when large numbers
of women were still using hormone therapy, the number of new breast
cancer cases fell by nearly 7 percent.
In taking a look at the three studies again, Shapiro and his
team reviewed whether the evidence satisfied criteria important to
researchers, such as the strength of an association, taking into
account other factors that could influence risk. Their conclusion:
The evidence is not strong enough to say definitively that hormone
therapy causes breast cancer.
The study is published in the current issue of the
Journal of Family Planning and Reproductive Health Care.
The new conclusion drew mixed reactions from experts.
In an editorial accompanying the study, Nick Panay, a consultant
gynecologist at the Queen Charlotte's & Chelsea Hospital in
London, supported the conclusions of the new analysis. "If there is
a risk, the risk is small, and the benefits of HRT can be
life-altering," he wrote. "It is vital that we keep this in
perspective when counseling our patients."
The hormone therapy in use today, Panay said, is lower in dose
than those used in the previous research. "In principle, we tend to
start with lower doses than we used to and increase as required
until full symptom relief has been achieved," he said.
What is needed now, he said, is a clinical trial in which the
hormone therapy in use today is compared with placebo, to evaluate
the risks and benefits.
Another expert took a more middle-of-the-road view about the
"It would be hard to say the entire decline [in breast cancer rates] is due to the decline in HRT use," said Dr. Steven Narod, the Canada Research Chair in Breast Cancer at the University of Toronto.
According to Dr. Susan Gapstur, vice president of epidemiology
for the American Cancer Society, the new analysis overlooks some
other important information. "Indeed, there is a much larger body
of scientific evidence from clinical trials and from observational
epidemiologic studies comparing breast cancer incidence rates in
women who used HRT to those who did not that demonstrate the risks
and benefits of HRT for chronic diseases," she said.
"Women need to discuss with their doctors the risk and benefits of taking HRT for the primary prevention of chronic disease, including breast cancer," she added.
Narod said hormone replacement is an excellent therapy for some
women. Therapy that includes progesterone carries more risk, he
said, and limiting use to five years or less seems wise.
Shapiro has performed consulting work for the manufacturers of
hormone therapy, and Panay has received grants from pharmaceutical
For more on hormone therapy after menopause, visit the
American Cancer Society.
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