title: Plasma leptin and breast cancer risk: a prospective study in northern Sweden.
abstract: BACKGROUND
  Obesity is associated with risk of breast cancer after menopause. Circulating levels of leptin are high in obesity and leptin stimulates growth of breast cancer cells.
  
  
  METHODS
  In a case-control study nested within the Northern Sweden Health and Disease Cohort, we measured leptin levels in prediagnostic plasma from 149 postmenopausal women who were diagnosed with breast cancer at a mean time 1.7 years (SD 2.0) after recruitment and among 258 control subjects.
  
  
  RESULTS
  No significant association between plasma levels of leptin and breast cancer risk was observed. Odds ratios (ORs) of breast cancer with increasing levels of leptin were 1.00 [referent], 1.01 [95% CI = 0.58-1.84], 0.65 [0.36-1.18], and 0.94 [0.53-1.67], and (p(for trend) = 0.54). Adjustment for smoking, body mass index, and plasma insulin did not affect risk estimates.
  
  
  CONCLUSIONS
  These data do not support the hypothesis that plasma leptin is a risk factor for breast cancer.
authors.affiliation: Department of Urology and Andrology, Umeå University Hospital, Umeå, Sweden.
authors.forename: Pär
authors.initials: P
authors.lastname: Stattin
authors.forename: Stefan
authors.initials: S
authors.lastname: Söderberg
authors.forename: Carine
authors.initials: C
authors.lastname: Biessy
authors.forename: Per
authors.initials: P
authors.lastname: Lenner
authors.forename: Göran
authors.initials: G
authors.lastname: Hallmans
authors.forename: Rudolf
authors.initials: R
authors.lastname: Kaaks
authors.forename: Tommy
authors.initials: T
authors.lastname: Olsson
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000209:etiology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D020738:Leptin / Q000097:blood*; D008875:Middle Aged; D016017:Odds Ratio; D011446:Prospective Studies; D012307:Risk Factors; D013548:Sweden
chemical_list: D020738:Leptin