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Recreational exercise may reduce the risk of breast cancer in older women, according to
new findings by the U.S. government research project, the Women’s Health Initiative.
Women over age 50 who engaged in the equivalent of 1.25 to 2.5 hours per week of brisk
walking reduced their risk of developing breast cancer by 18%, compared with women who did
not exercise. The effect was greatest in women who exercised the most frequency.
Researchers say the study highlights the fact that post-menopausal women need not engage
in strenuous activity to reduce their risk of breast cancer.
The Women’s Health Initiative was established by the National Institutes of Health
in 1991 to address the most common causes of death, disability, and impaired quality of
life in post-menopausal women. The project will run a total of 15 years and investigate cardiovascular disease, cancer,
and osteoporosis. The main components of the Women’s Health
Initiative are three studies: the Hormone Replacement Therapy
Trial (HRT), the Dietary Modification Trial (DM), and the Calcium/Vitamin D
Supplementation Trial (CaD).
The latest results of the Women’s Health Initiative were published by Anne
McTiernan, M.D., Ph.D. of the Fred Hutchinson Cancer Research Center in Seattle,
Washington and colleagues; the results appear in the September 10, 2003 issue of the Journal
of the American Medical Association.
The current findings are based on an analysis of 74,171 women between the ages of 50
and 79 from 40 U.S. clinical centers who participated in the Women's Health Initiative
study from 1993 to 1998. Dr. McTiernan and her team found that women who walked briskly
for 1.25 to 2.5 hours per week reduced their risk of breast cancer by 18%. A slightly
greater reduction in breast cancer risk was seen in women who engaged in 10 hours of
exercise (equivalent to brisk walking) per week. The reduction in breast cancer risk was
greatest for women with low body masses but
was also seen in women with middle body masses.
Dr. McTiernan and her colleagues conclude that "increased physical activity is
associated with reduced risk for breast cancer in postmenopausal women, longer duration
provides most benefit, and that such activity need not be strenuous."
The effects of exercise on health have been well documented. In another study published
in the same issue of the Journal of the American Medical Association, John M.
Jakicic, Ph.D. of the University of Pittsburgh and colleagues found that a combination of
diet and exercise over a 12 month period enables women to lose weight and improve
cardiovascular fitness. Previous research has shown that exercise can also help older
people remain active and disease free for long periods.
Additional Resources and References
- The reports, "Recreational Physical Activity and the Risk of Breast Cancer in
Postmenopausal Women: The Women's Health Initiative Cohort Study," and "Effect
of Exercise Duration and Intensity on Weight Loss in Overweight, Sedentary Women,"
are published in the September 10, 2003 issue of the Journal of the American Medical
Association, http://jama.ama-assn.org/
- For information on the Women’s Health Initiative, please visit http://www.nhlbi.nih.gov/whi/
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