title: Hyperinsulinaemia and increased risk of breast cancer: findings from the British Women's Heart and Health Study.
abstract: OBJECTIVE
  To assess the association between fasting insulin levels and breast cancer.
  
  
  METHODS
  Cross sectional study.
  
  
  METHODS
  3868 women aged 60-79 years.
  
  
  METHODS
  Prevalent breast cancer (151 cases).
  
  
  RESULTS
  Insulin levels were positively associated with breast cancer. The age adjusted odds ratio (95% confidence interval) for a one unit increase in log(e) insulin levels among women without diabetes was 1.34 (1.02, 1.77). This association was not substantively altered by adjustment for potential confounding factors (age of menopause, hysterectomy/oophorectomy, hormone replacement use, oral contraceptive use, parity, adult social class and smoking) or potential mediating factors (body mass index, waist to hip ratio, leg length, age at menarche and childhood social class). Women with both long legs and higher insulin levels were at particularly increased risk, with breast cancer prevalence being 5.7% among women in the highest thirds of both insulin levels and leg-length compared to 1.8% among those in the lowest thirds of both. Positive associations between insulin levels and breast cancer were found for both pre- and post-menopausal breast cancers. Fasting glucose levels, HOMA score, diabetes and a history of gestational glycosuria or diabetes were also positively associated with breast cancer
  
  
  CONCLUSIONS
  Hyperinsulinaemia is positively associated with breast cancer in this cohort of older women. This effect may be mediated via a number of hormonal pathways acting at different stages of the life course.
authors.affiliation: Department of Social Medicine, University of Bristol, Canynge Hall, Whiteladies Road, Bristol BS8 2PR, UK. d.a.lawlor@bristol.ac.uk
authors.forename: Debbie A
authors.initials: DA
authors.lastname: Lawlor
authors.forename: George Davey
authors.initials: GD
authors.lastname: Smith
authors.forename: Shah
authors.initials: S
authors.lastname: Ebrahim
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006946:Hyperinsulinism / Q000150:complications*; D008297:Male; D008593:Menopause; D008875:Middle Aged; D016017:Odds Ratio; D015995:Prevalence; D018570:Risk Assessment; D006113:United Kingdom / Q000453:epidemiology