title: Effects of a moderate intensity exercise intervention on estrogen metabolism in postmenopausal women.
abstract: Physical activity has been associated with reduced breast cancer risk, potentially via hormonal pathways, and high urinary excretion of 2-hydroxyestrone (2-OH E(1)) relative to 16alpha-hydroxyestrone (16alpha-OH E(1)) also has been associated with reduced breast cancer risk. Studies suggest that body composition and exercise can influence estrogen metabolism. We determined the effects of a 12-month moderate intensity aerobic exercise intervention on urinary 2-OH E(1), 16alpha-OH E(1), and their ratio in overweight and obese, previously sedentary, postmenopausal women, ages 50-75 years. Women were randomized to a 12-month exercise intervention (n = 87) or stretching control group (n = 86); 170 completed the study. Urinary 2- and 16alpha-OH E(1) were measured in spot urines collected at baseline, 3, and 12 months. Body composition was measured at baseline and 12 months. Differences between exercisers and controls for excretion of estrogen metabolites were determined using general estimating equations. Further analyses assessed change in estrogen metabolites and their ratio by subgroups of change in body composition. Overall, there were no significant effects of the exercise intervention on 2-OH E(1), 16alpha-OH E(1), or their ratio (P > 0.05). There appeared to be an effect of change in intra-abdominal fat and adherence to the exercise intervention on change in the estrogen metabolites or their ratio. However, this did not reflect a potentially desirable change in estrogen metabolites associated with the exercise intervention. Thus, this 12-month moderate intensity exercise intervention did not significantly alter urinary excretion of 2-OH E(1), 16alpha-OH E(1), or their ratio in this population of women.
authors.affiliation: Cancer Prevention Program, Fred Hutchinson Cancer Research Center, P. O. Box 19024, Seattle, WA 98109, USA.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Atkinson
authors.forename: Johanna W
authors.initials: JW
authors.lastname: Lampe
authors.forename: Shelley S
authors.initials: SS
authors.lastname: Tworoger
authors.forename: Cornelia M
authors.initials: CM
authors.lastname: Ulrich
authors.forename: Deborah
authors.initials: D
authors.lastname: Bowen
authors.forename: Melinda L
authors.initials: ML
authors.lastname: Irwin
authors.forename: Robert S
authors.initials: RS
authors.lastname: Schwartz
authors.forename: Bharat K
authors.initials: BK
authors.lastname: Rajan
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yasui
authors.forename: John D
authors.initials: JD
authors.lastname: Potter
authors.forename: Anne
authors.initials: A
authors.lastname: McTiernan
mesh_terms: D000368:Aged; D001823:Body Composition; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000517:prevention & control; D016001:Confidence Intervals; D003404:Creatinine / Q000378:metabolism* / Q000652:urine; D004967:Estrogens / Q000378:metabolism* / Q000652:urine; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D010809:Physical Fitness / Q000502:physiology; D017698:Postmenopause; D012016:Reference Values; D013997:Time Factors
chemical_list: D004967:Estrogens; D003404:Creatinine