Wednesday, February 17, 2010 (Last Updated: 02/18/2010)
WEDNESDAY, Feb. 17 (HealthDay News) -- In previously inactive, mostly overweight, postmenopausal women, participation in a program of moderate-to-vigorous aerobic exercise may result in sex hormone changes that are associated with a reduced risk of breast cancer, according to a study published online Feb. 16 in the Journal of Clinical Oncology.
Christine M. Friedenreich, Ph.D., of Alberta Health Services in Calgary, Canada, and colleagues randomly assigned 320 postmenopausal, sedentary women, aged 50 to 74 years, to 225 minutes per week of aerobic exercise or their usual level of activity.
After 12 months, the researchers found that exercise was associated with significant reductions in estradiol and free estradiol (treatment effect ratios, 0.93 and 0.91, respectively) and increases in sex hormone-binding globulin (treatment effect ratio, 1.04). They observed no significant group differences in levels of estrone, androstenedione, and testosterone.
"While the study successfully addressed its objectives, the modest reduction in estrogen levels seen is unlikely to mediate any major reduction in breast cancer. The authors acknowledge this when they suggest that physical activity may be an acceptable means of breast cancer risk reduction only in those whose risk does not warrant use of chemoprevention intervention," writes the author of an accompanying editorial.
The author of the accompanying editorial reported financial relationships with several pharmaceutical companies.
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