title: Relationship between breast cancer risk factors and mammographic breast density in the Fernald Community Cohort.
abstract: BACKGROUND
  We investigated associations of known breast cancer risk factors with breast density, a well-established and very strong predictor of breast cancer risk.
  
  
  METHODS
  This nested case-control study included breast cancer-free women, 265 with high and 860 with low breast density. Women were required to be 40-80 years old and should have a body mass index (BMI) <35 at the time of the index mammogram. Information on covariates was obtained from annual questionnaires.
  
  
  RESULTS
  In the overall analysis, breast density was inversely associated with BMI at mammogram (P for trend<0.001), and parity (P for trend=0.02) and positively associated with alcohol consumption (ever vs never: odds ratio 2.0, 95% confidence interval 1.4-2.8). Alcohol consumption was positively associated with density, and the association was stronger in women with a family history of breast cancer (P<0.001) and in women with hormone replacement therapy (HRT) history (P<0.001). Parity was inversely associated with density in all subsets, except premenopausal women and women without a family history. The association of parity with density was stronger in women with HRT history (P<0.001).
  
  
  CONCLUSIONS
  The associations of alcohol and parity with breast density appear to be in reverse direction, but stronger in women with a family history of breast cancer and women who ever used HRT.
authors.affiliation: Department of Environmental Health, University of Cincinnati College of Medicine, PO Box 670056, Cincinnati, OH 45267, USA.
authors.forename: L
authors.initials: L
authors.lastname: Yaghjyan
authors.forename: M C
authors.initials: MC
authors.lastname: Mahoney
authors.forename: P
authors.initials: P
authors.lastname: Succop
authors.forename: R
authors.initials: R
authors.lastname: Wones
authors.forename: J
authors.initials: J
authors.lastname: Buckholz
authors.forename: S M
authors.initials: SM
authors.lastname: Pinney
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000428:Alcohol Drinking; D015992:Body Mass Index; D001940:Breast / Q000033:anatomy & histology*; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D055088:Early Detection of Cancer; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D010298:Parity; D011247:Pregnancy; D012307:Risk Factors