title: Alcohol consumption, endogenous estrogen and mammographic density among premenopausal women.
abstract: BACKGROUND
  Alcohol consumption may promote aromatization of androgens to estrogens, which may partly explain the observations linking alcohol consumption to higher breast cancer risk. Whether alcohol consumption is associated with endogenous estrogen levels, and mammographic density phenotypes in premenopausal women remains unclear.
  
  
  METHODS
  Alcohol consumption was collected by self-report and interview, using semi quantitative food frequency questionnaires, and a food diary during seven days of a menstrual cycle among 202 premenopausal women, participating in the Energy Balance and Breast Cancer Aspects (EBBA) study I. Estrogen was assessed in serum and daily in saliva across an entire menstrual cycle. Computer-assisted mammographic density (Madena) was obtained from digitized mammograms taken between days 7-12 of the menstrual cycle. Multivariable regression models were used to investigate the associations between alcohol consumption, endogenous estrogen and mammographic density phenotypes.
  
  
  RESULTS
  Current alcohol consumption was positively associated with endogenous estrogen, and absolute mammographic density. We observed 18 % higher mean salivary 17β-estradiol levels throughout the menstrual cycle, among women who consumed more than 10 g of alcohol per day compared to women who consumed less than 10 g of alcohol per day (p = 0.034). Long-term and past-year alcohol consumption was positively associated with mammographic density. We observed a positive association between alcohol consumption (past year) and absolute mammographic density; high alcohol consumers (≥7 drinks/week) had a mean absolute mammographic density of 46.17 cm(2) (95 % confidence interval (CI) 39.39, 52.95), while low alcohol consumers (<1 drink/week) had a mean absolute mammographic density of 31.26 cm(2) (95 % CI 25.89, 36.64) (p-trend 0.001). After adjustments, high consumers of alcohol (≥7 drinks/week), had 5.08 (95 % CI 1.82, 14.20) times higher odds of having absolute mammographic density above median (>32.4 cm(2)), compared to low (<1 drink/week) alcohol consumers.
  
  
  CONCLUSIONS
  Alcohol consumption was positively associated with daily endogenous estrogen levels and mammographic density in premenopausal women. These associations could point to an important area of breast cancer prevention.
authors.affiliation: The Cancer Centre, Oslo University Hospital, 0424, Oslo, Norway. hanne.frydenberg@medisin.uio.no.
authors.forename: Hanne
authors.initials: H
authors.lastname: Frydenberg
authors.affiliation: The Cancer Centre, Oslo University Hospital, 0424, Oslo, Norway. vidarflote@yahoo.no.
authors.forename: Vidar G
authors.initials: VG
authors.lastname: Flote
authors.affiliation: The Cancer Centre, Oslo University Hospital, 0424, Oslo, Norway. inelar@ous-hf.no.
authors.forename: Ine M
authors.initials: IM
authors.lastname: Larsson
authors.affiliation: Department of Obstetrics and Gynecology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Box 668, Rochester, NY, 14534, USA. Emily_Barrett@urmc.rochester.edu.
authors.forename: Emily S
authors.initials: ES
authors.lastname: Barrett
authors.affiliation: Department of Community Medicine, Faculty of Health Sciences, The Arctic University of Norway, 9037, Tromsø, Norway. anne-sofie.furberg@uit.no.
authors.forename: Anne-Sofie
authors.initials: AS
authors.lastname: Furberg
authors.affiliation: Cancer Registry of Norway, PO Box 5313, Majorstuen, 0304, Oslo, Norway. giske.ursin@kreftregisteret.no.
authors.forename: Giske
authors.initials: G
authors.lastname: Ursin
authors.affiliation: Department of Community Medicine, Faculty of Health Sciences, The Arctic University of Norway, 9037, Tromsø, Norway. tom.wilsgaard@uit.no.
authors.forename: Tom
authors.initials: T
authors.lastname: Wilsgaard
authors.affiliation: Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA. pellison@fas.harvard.edu.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Ellison
authors.affiliation: Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA. amctiern@fhcrc.org.
authors.forename: Anne
authors.initials: A
authors.lastname: McTiernan
authors.affiliation: Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, 0316, Oslo, Norway. anette.hjartaker@medisin.uio.no.
authors.forename: Anette
authors.initials: A
authors.lastname: Hjartåker
authors.affiliation: Department of Environmental Health, Jagiellonian University Collegium Medicum, 31-531, Krakow, Poland. mbjasien@cyf-kr.edu.pl.
authors.forename: Grazyna
authors.initials: G
authors.lastname: Jasienska
authors.affiliation: The Cancer Centre, Oslo University Hospital, 0424, Oslo, Norway. inger.thune@uit.no.|Department of Community Medicine, Faculty of Health Sciences, The Arctic University of Norway, 9037, Tromsø, Norway. inger.thune@uit.no.
authors.forename: Inger
authors.initials: I
authors.lastname: Thune
mesh_terms: D000328:Adult; D000428:Alcohol Drinking; D000071060:Breast Density; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D004967:Estrogens / Q000097:blood*; D005260:Female; D006801:Humans; D042361:Mammary Glands, Human / Q000002:abnormalities*; D009664:Norway / Q000453:epidemiology; D017697:Premenopause
chemical_list: D004967:Estrogens