title: Association of Active and Sedentary Behaviors with Postmenopausal Estrogen Metabolism.
abstract: OBJECTIVE
  Physical activity may reduce endogenous estrogens, but few studies have assessed effects on estrogen metabolism and none have evaluated sedentary behavior in relation to estrogen metabolism. We assessed relationships between accelerometer-measured physical activity and sedentary behavior and 15 urinary estrogens and estrogen metabolites (EM) among postmenopausal controls from a population-based breast cancer case-control study conducted in Poland (2000-2003).
  
  
  METHODS
  Postmenopausal women (N = 542) were ages 40 to 72 yr and not currently using hormone therapy. Accelerometers, worn for 7 d, were used to derive measures of average activity (counts per day) and sedentary behavior (<100 counts per minute per day). Estrogen metabolites were measured in 12-h urine samples using liquid chromatography-tandem mass spectrometry. Estrogen metabolites were analyzed individually, in metabolic pathways (C-2, -4, or -16), and as ratios relative to parent estrogens. Geometric means of estrogen metabolites by tertiles of accelerometer-measures, adjusted for age and body mass, were computed using linear models.
  
  
  RESULTS
  High activity was associated with lower levels of estrone and estradiol (P trend = 0.01), whereas increased sedentary time was positively associated with these parent estrogens (P trend = 0.04). Inverse associations were observed between high activity and 2-methoxyestradiol, 4-methoxyestradiol, 17-epiestriol, and 16-epiestriol (P trend = 0.03). Sedentary time was positively associated with methylated catechols in the 2- and 4-hydroxylation pathways (P trend ≤ 0.04). Women in the highest tertile of activity had increased hydroxylation at the C-2, -4, and -16 sites relative to parent estrogens (P trend ≤ 0.02), whereas increased sedentary time was associated with a lower 16-pathway/parent estrogen ratio (P trend = 0.01).
  
  
  CONCLUSIONS
  Higher activity was associated with lower urinary estrogens, possibly through increased estrogen hydroxylation and subsequent metabolism, whereas sedentary behavior may reduce metabolism.
authors.affiliation: 1Department of Epidemiology and Biostatistics, University of Maryland School of Public Health, College Park, MD; 2Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD; 3Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD; 4Biostatistics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD; 5Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA; 6M. Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, POLAND; 7Division of Breast Cancer Research, Division of Genetics and Epidemiology and Breakthrough Breast Cancer Centre, The Institute of Cancer Research, London, UNITED KINGDOM; 8Laboratory of Proteomics and Analytical Technologies, Advanced Technology Program, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD; and 9C2N Diagnostics, Saint Louis, MO.
authors.forename: Cher M
authors.initials: CM
authors.lastname: Dallal
authors.forename: Louise A
authors.initials: LA
authors.lastname: Brinton
authors.forename: Charles E
authors.initials: CE
authors.lastname: Matthews
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Pfeiffer
authors.forename: Terryl J
authors.initials: TJ
authors.lastname: Hartman
authors.forename: Jolanta
authors.initials: J
authors.lastname: Lissowska
authors.forename: Roni T
authors.initials: RT
authors.lastname: Falk
authors.forename: Montserrat
authors.initials: M
authors.lastname: Garcia-Closas
authors.forename: Xia
authors.initials: X
authors.lastname: Xu
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Veenstra
authors.forename: Gretchen L
authors.initials: GL
authors.lastname: Gierach
mesh_terms: D000077584:2-Methoxyestradiol; D061725:Accelerometry; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D004958:Estradiol / Q000031:analogs & derivatives / Q000652:urine; D004964:Estriol / Q000652:urine; D004967:Estrogens / Q000378:metabolism* / Q000652:urine; D004970:Estrone / Q000652:urine; D015444:Exercise; D005260:Female; D006801:Humans; D008875:Middle Aged; D011044:Poland; D017698:Postmenopause; D057185:Sedentary Behavior
chemical_list: D004967:Estrogens; C045018:4-methoxyestradiol; D004970:Estrone; D004958:Estradiol; D000077584:2-Methoxyestradiol; D004964:Estriol