title: Breast-feeding and risk of epithelial ovarian cancer.
abstract: OBJECTIVE
  Evidence suggests that breast-feeding may decrease the risk of epithelial ovarian cancer but it is not clear whether there is a relationship with duration of breast-feeding, patterns of breast-feeding, or particular histological subtypes of ovarian cancer. We sought to investigate these issues in detail.
  
  
  METHODS
  Data from participants in a population-based study of ovarian cancer in western Washington State, USA (2002-2007) who had had at least one birth (881 cases and 1,345 controls) were used to assess relations between patterns of breast-feeding and ovarian cancer. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI).
  
  
  RESULTS
  Women who ever breast-fed had a 22 % reduction in risk of ovarian cancer compared with those who never breast-fed (OR = 0.78, 95% CI 0.64-0.96) and risk reduction appeared greater with longer durations of feeding per child breast-fed (OR = 0.56, 95% CI 0.32-0.98 for 18 months average duration breast-feeding versus none). Introduction of supplementary feeds did not substantially alter these effects. The overall risk reduction appeared greatest for the endometrioid and clear cell subtypes (OR per month of average breast-feeding per child breast-fed = 0.944, 95% CI 0.903-0.987).
  
  
  CONCLUSIONS
  Among women who have had the opportunity to breast-feed, ever breast-feeding and increasing durations of episodes of breast-feeding for each breast-fed child are associated with a decrease in the risk of ovarian cancer independent of numbers of births, which may be strongest for the endometrioid subtype.
authors.affiliation: School of Population Health, The University of Queensland, Herston, Australia. susan.jordan@qimr.edu.au
authors.forename: S J
authors.initials: SJ
authors.lastname: Jordan
authors.forename: K L
authors.initials: KL
authors.lastname: Cushing-Haugen
authors.forename: K G
authors.initials: KG
authors.lastname: Wicklund
authors.forename: J A
authors.initials: JA
authors.lastname: Doherty
authors.forename: M A
authors.initials: MA
authors.lastname: Rossing
mesh_terms: D000328:Adult; D000368:Aged; D001942:Breast Feeding / Q000706:statistics & numerical data*; D000077216:Carcinoma, Ovarian Epithelial; D016022:Case-Control Studies; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D009375:Neoplasms, Glandular and Epithelial / Q000453:epidemiology* / Q000517:prevention & control; D016017:Odds Ratio; D010051:Ovarian Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D012307:Risk Factors; D014861:Washington / Q000453:epidemiology