|
The use
of estrogen and progestin in combination is strongly linked
to the risk of breast cancer, heart attack, stroke and blood
clots, according to U.S. researchers.
The National
Heart, Lung and Blood Institute (NHLBI) of the National Institutes
of Health (NIH) has halted a major clinical trial of combined
estrogen and progestin in healthy menopausal women due to
an increased risk of invasive breast cancer. The trial also
found increases in coronary heart disease, stroke, and pulmonary
embolism in women taking the combination therapy.
Approximately
6 million women in the United States are taking estrogen plus
progestin for relief of menopausal symptoms or long-term health
reasons.
The trial,
a component of the Women's Health Initiative (WHI), included
16,608 women ages 50 to 79 who had not had a hysterectomy.
The women were given a combination of estrogen and progestin
or a placebo. The trial was slated to run 8.5 years, but was
halted after 5.2 years.
Researchers
found that the combination therapy reduced the women's risk
of developing colon cancer and hip fractures, but the harm
was greater than the benefit, concluded the NIH. A report
on the study was released by the Journal of the American Medical
Association in an expedited article due for publication later
this month.
"We
have long sought the answer to the question: Does postmenopausal
hormone therapy prevent heart disease and, if it does, what
are the risks? The bottom-line answer from WHI is that this
combined form of hormone therapy is unlikely to benefit the
heart. The cardiovascular and cancer risks of estrogen plus
progestin outweigh any benefits - and a 26 percent increase
in breast cancer risk is too high a price to pay, even if
there were a heart benefit. Similarly, the risks outweigh
the benefits of fewer hip fractures," said Dr. Claude
Lenfant, NHLBI Director.
Specific
WHI study findings for the combination hormone therapy group
compared to placebo include:
- a 41
percent increase in strokes;
- a 29
percent increase in heart attacks;
- a doubling
of rates of blood clots;
- a 22
percent increase in total cardiovascular disease;
- a 26
percent increase in breast cancer;
- a 37
percent reduction in cases of colorectal cancer;
- a one-third
reduction in the rates of hip fractures;
- a 24
percent reduction in total fractures; and
- no
difference in total mortality (from all causes).
In a second
study, published in the journal Cancer Epidemiology, Biomarkers
and Prevention, investigators reported on a study that analyzed
the type and duration of postmenopausal hormone therapy and
the risk of breast cancer.
A total
of 5,298 postmenopausal women between the ages of 50 to 79
were included in the study. The women all had a new diagnosis
of invasive breast cancer. A control group of 5,571 women
was also included in the study.
Participants
completed a telephone interview covering hormone use and breast
cancer risk factors.
Researchers
found that the relative risk for breast cancer increased with
longer durations of hormone use. The rate was 2.2 percent
per year for estrogen alone and 4 percent per year for estrogen-progestin
use. Estrogen-progestin use that was both recent and long-term
was more strongly linked with the risk of breast cancer than
similar use of estrogen alone.
The use
of progestin alone was linked with a doubling of risk for
breast cancer. Use of estrogen and progestin appeared to be
more strongly linked with risk of breast cancer than estrogen
alone, concluded the researchers.
Source:
Breast Cancer
Week of July 14, 2002
|
HOME PAGE
