Exercise can have beneficial effects on breast cancer risk as previous research has indicated. The research reviewed is interesting because it may explain why exercise reduces the risk for breast cancer (Smith AJ, et.al.,2013). The research participants were sedentary, healthy young women who did 30 minutes of moderate to vigorous aerobic exercise five times a week for approximately 16 weeks. They were compared with a controlled group which did not exercise. Estrogen, estradiol and estriol and nine estrogen metabolites were measured at the start of the study and also at the end. As expected, the exercise resulted in a significant increase in aerobic fitness and lean body mass plus a significant decrease in body fat percentage. What was especially interesting was that the exercise also significantly increased the ratio between 2-hydroxyestrone to 16alpha-hydroxyestrone. These are estrogen metabolites, and the increased ratio between them could be the reason why exercise lowers breast cancer risk. Cancer Epidemiol Biomarkers Prev. 2013 May;22(5):756-64. doi: 10.1158/1055-9965.EPI-12-1325. The effects of aerobic exercise on estrogen metabolism in healthy premenopausal women. Smith AJ, Phipps WR, Thomas W, Schmitz KH, Kurzer MS. Source Department of Food Science and Nutrition, School of Public Health, University of Minnesota, Minneapolis, MN 55108, USA. Abstract BACKGROUND: It is well accepted that exercise can decrease breast cancer risk. Limited clinical evidence suggests that this risk could be mediated through changes in estrogen metabolism in premenopausal women. Our objective was to investigate the effects of exercise on premenopausal estrogen metabolism pertinent to breast cancer risk. METHODS: Sedentary, healthy, young eumenorrheic women were randomized into an intervention of 30 minutes of moderate-to-vigorous aerobic exercise five times a week for approximately 16 weeks (n = 212), or into a usual-lifestyle sedentary control group (n = 179). Urinary levels of estrogens [estrone [E1], estradiol, and estriol] and nine estrogen metabolites were measured at baseline and at study end by liquid chromatography/tandem mass spectrometry. The ratios of 2-hydroxyestrone to 16α-hydroxyestrone (2-OHE1/16α-OHE1) and 2-OHE1 to 4-hydroxyestrone (2- OHE1/4-OHE1) were also calculated. RESULTS: The exercise intervention resulted in significant increases in aerobic fitness and lean body mass and a significant decrease in percent body fat. For exercisers who completed the study (n = 165), 2-OHE1/16α-OHE1 increased significantly (P = 0.043), whereas E1 decreased significantly (P = 0.030) in control participants (n = 153). The change from baseline in 2-OHE1/16α-OHE1 was significantly different between groups (P = 0.045), even after adjustment for baseline values. CONCLUSIONS: The exercise intervention resulted in a significant increase in the 2-OHE1/16α-OHE1 ratio but no differences in other estrogen metabolites or ratios. IMPACT: Our results suggest that changes in premenopausal estrogen metabolism may be a mechanism by which increased physical activity lowers breast cancer risk. Cancer Epidemiol Biomarkers Prev. 2007 Apr;16(4):731-9. Effects of aerobic exercise training on estrogen metabolism in premenopausal women: a randomized controlled trial. Campbell KL, Westerlind KC, Harber VJ, Bell GJ, Mackey JR, Courneya KS. Source E-488 Van Vliet Centre, Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada T6G 2H9. Abstract BACKGROUND: Regular physical activity may alter estrogen metabolism, a proposed biomarker of breast cancer risk, by shifting metabolism to favor production of 2-hydroxyestrone (2-OHE1). Few studies, however, have examined this question using a randomized controlled trial. PURPOSE: To examine the effects of 12 weeks of aerobic exercise training on 2-OHE1 and 16alpha-hydroxyestrone (16alpha-OHE1) in premenopausal women. METHODS: Participants were healthy, regularly menstruating, Caucasian women, 20 to 35 years, body mass index of 18 to 29.9, not using pharmacologic contraceptives, with average or below average fitness [maximal oxygen consumption (VO(2max)),
Posted on: Sun, 07 Jul 2013 18:38:43 +0000
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