|
E-mail this page to a friend!
Estrogen May Increase Blood Clots in Postmenopausal
Women, Breast Cancer in Blacks
April 11, 2006 - Estrogen therapy may increase the
risk of venous thrombosis, the formation of blood clots in the veins,
among postmenopausal women who have had their uterus removed, according
to a study in the April 10 issue of the Archives of Internal Medicine,
one of the JAMA/Archives journals. Another study in this issue says
hormone therapy, including estrogen, appears to be associated with
increased risk of breast cancer among black women.
(See
breast cancer report below this story on blood clots.)
Venous thromboembolism (VT), which includes the
conditions deep vein thrombosis (a blood clot in a deep vein) and
pulmonary embolism (a blood clot that travels to the lungs), affects
about one adult per 1,000 years of life, according to background
information in the article.
Researchers suspect that hormone therapy may
increase a woman's risk of developing VT. The largest study analyzing
the relationship between hormone therapy and VT is the Women's Health
Initiative (WHI), which included two large clinical trials. One WHI
trial examined the effects of estrogen plus progestin and found that
this combination of hormones appeared to increase the risk of VT.
J. David Curb, M.D., University of Hawaii and
Pacific Health Research Institute, Honolulu, and colleagues analyzed
data from the other WHI trial, in which the effect of estrogen alone was
studied in 10,739 women aged 50 to 79 years. The participants were
randomly assigned to take either combined equine estrogens, a mix of
several estrogens or placebo. They were followed for an average of 7.1
years, during which 197 women developed VT, including 144 with deep vein
thrombosis, 91 with pulmonary embolism and 38 with both.
Of those 197 women who developed VT, 111 were
taking estrogen and 86 were taking placebo. The risk of VT was slightly
higher for women receiving estrogen therapy; was significantly increased
for deep venous thrombosis, but not significantly increased for
pulmonary embolism; and was highest in the first two years of therapy.
Estrogen therapy appeared to affect risk more in women with higher
physical activity levels and lower HDL (good) cholesterol. Overall, the
risk of venous thrombosis associated with estrogen therapy was lower
than that associated with estrogen plus progestin in the other WHI
trial.
"Our data suggest that although the absolute
incidence is relatively low, the use of combined equine estrogens
increases the relative risk of venous thrombosis in postmenopausal women
without a uterus," the authors conclude. "Women with appropriate
indications, such as short-term treatment of severe menopausal symptoms,
should use combined equine estrogens only after careful consideration of
the relative risks and benefits, especially if the women have other risk
factors for venous thrombosis," which include older age, obesity and a
history of the condition.
The Netherlands Heart Foundation provided funding
for genetic analyses.
Hormone Use Linked To Increased Breast Cancer Risk
Among Black Women
Hormone therapy appears to be associated with
increased risk of breast cancer among black women, with a stronger link
for leaner women, according to a second study in the April 10 issue of the
Archives of Internal Medicine, one of the JAMA/Archives journals.
Previous research has suggested that the long-term
use of female hormone therapy is associated with an increased risk of
developing breast cancer, according to background information in the
article. However, most of the women in the largest studies have been
white, and few studies have looked at the risks specifically in black
women.
Lynn Rosenberg, Sc.D., of Slone Epidemiology
Center, Boston University, and colleagues examined the association in
23,191 women age 40 years or older who were part of the Black Women's
Health Study, conducted by investigators at Boston University and Howard
University, Washington, D.C.
The participants filled out an initial
questionnaire about medical history, menopausal status and hormone use
when they enrolled in the study in 1995. Follow-up questionnaires that
also included questions about the development of breast cancer were
completed every two years through the year 2003. The women's body mass
index (BMI) was calculated by dividing their weight in kilograms by the
square of their height in meters.
During the course of the study, 615 cases of breast
cancer were reported. Breast cancer was more likely to occur in women
who had taken hormones, including estrogen or estrogen plus progestin,
in the previous two years than in women who had never taken hormones.
The longer a woman took hormones, the more likely she was to develop
breast cancer, and the risk was slightly higher for women taking
estrogen with progestin than for those taking progestin alone. The
association between hormone use and breast cancer was strongest for
women who were lean, defined as having a BMI of less than 25.
"Associations of exogenous [supplemental] female
hormone use with increased risk of breast cancer are biologically
plausible," the authors write. Estrogens produced by the body are
associated with the development of breast cancer, and progestin is known
to induce cell division in breast tissue, which could lead to a higher
risk of cancer. The relationship may be stronger in lean women because
fat tissue produces estrogen, so the extra hormones added by taking
pills may not have as much of an effect on estrogen levels in heavier
women.
"These results based on data from U.S. black women
strengthen the evidence that use of estrogen alone and estrogen with
progestin increases the risk of breast cancer and that the association
is stronger among leaner women," the authors conclude.
This study was supported by a grant from the
National Cancer Institute, Bethesda, Md.
Click here to Search SeniorJournal.com for more on
this subject
Click to More Senior News on the
Front Page
Copyright: SeniorJournal.com |
