title: Plasma adiponectin concentrations and risk of incident breast cancer.
abstract: BACKGROUND
  Previous retrospective case-control studies suggest that adiponectin, an obesity-related hormone, is inversely associated with breast cancer risk, particularly in postmenopausal women; however, no prospective studies exist. Therefore, we conducted a prospective case-control study nested within the Nurses' Health Study (NHS) and NHSII cohorts examining the association between plasma adiponectin concentrations and breast cancer risk.
  
  
  METHODS
  Blood samples were collected from 1989 through 1990 (NHS) and 1996 through 1999 (NHSII); adiponectin was measured by RIA. The analysis included 1477 breast cancer cases diagnosed after blood collection and before June 2000 (NHS) or June 2003 (NHSII) who had one or two controls (n=2196) matched on age, menopausal status, postmenopausal hormone (PMH) use, fasting, and time of day and month of blood collection. We adjusted for body mass index at age 18, weight change from age 18 to blood draw, family history of breast cancer, history of benign breast disease, duration of PMH use, ages at menarche and first birth, and parity.
  
  
  RESULTS
  Although we observed no association between adiponectin and breast cancer risk overall, there was a nearly significant interaction by menopausal status (P=0.08), with a relative risk, top vs. bottom quartile of 0.73 (95% confidence interval, 0.55-0.98; P trend=0.08) among postmenopausal women and 1.30 (95% confidence interval, 0.80-2.10; P trend=0.09) for premenopausal women. Among postmenopausal women, adiponectin appeared more strongly inversely associated in women who never used PMH (P heterogeneity=0.05) and women with low circulating estradiol levels (P heterogeneity=0.05).
  
  
  CONCLUSIONS
  Our results suggest that adiponectin may be inversely associated with postmenopausal breast cancer risk, particularly in a low-estrogen environment.
authors.affiliation: Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Third Floor, Boston, Massachusetts 02115, USA. nhsst@channing.harvard.edu
authors.forename: Shelley S
authors.initials: SS
authors.lastname: Tworoger
authors.forename: A Heather
authors.initials: AH
authors.lastname: Eliassen
authors.forename: Theodoros
authors.initials: T
authors.lastname: Kelesidis
authors.forename: Graham A
authors.initials: GA
authors.lastname: Colditz
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
authors.forename: Christos S
authors.initials: CS
authors.lastname: Mantzoros
authors.forename: Susan E
authors.initials: SE
authors.lastname: Hankinson
mesh_terms: D052242:Adiponectin / Q000097:blood*; D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008593:Menopause; D008875:Middle Aged; D017698:Postmenopause; D011863:Radioimmunoassay
chemical_list: D052242:Adiponectin