title: Diabetes and breast cancer risk: a meta-analysis.
abstract: BACKGROUND
  The potential of an increased risk of breast cancer in women with diabetes has been the subject of a great deal of recent research.
  
  
  METHODS
  A meta-analysis was undertaken using a random effects model to investigate the association between diabetes and breast cancer risk.
  
  
  RESULTS
  Thirty-nine independent risk estimates were available from observational epidemiological studies. The summary relative risk (SRR) for breast cancer in women with diabetes was 1.27 (95% confidence interval (CI), 1.16-1.39) with no evidence of publication bias. Prospective studies showed a lower risk (SRR 1.23 (95% CI, 1.12-1.35)) than retrospective studies (SRR 1.36 (95% CI, 1.13-1.63)). Type 1 diabetes, or diabetes in pre-menopausal women, were not associated with risk of breast cancer (SRR 1.00 (95% CI, 0.74-1.35) and SRR 0.86 (95% CI, 0.66-1.12), respectively). Studies adjusting for body mass index (BMI) showed lower estimates (SRR 1.16 (95% CI, 1.08-1.24)) as compared with those studies that were not adjusted for BMI (SRR 1.33 (95% CI, 1.18-1.51)).
  
  
  CONCLUSIONS
  The risk of breast cancer in women with type 2 diabetes is increased by 27%, a figure that decreased to 16% after adjustment for BMI. No increased risk was seen for women at pre-menopausal ages or with type 1 diabetes.
authors.affiliation: International Prevention Research Institute, 95 cours Lafayette, 69006 Lyon, France.
authors.forename: P
authors.initials: P
authors.lastname: Boyle
authors.forename: M
authors.initials: M
authors.lastname: Boniol
authors.forename: A
authors.initials: A
authors.lastname: Koechlin
authors.forename: C
authors.initials: C
authors.lastname: Robertson
authors.forename: F
authors.initials: F
authors.lastname: Valentini
authors.forename: K
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authors.lastname: Coppens
authors.forename: L-L
authors.initials: LL
authors.lastname: Fairley
authors.forename: M
authors.initials: M
authors.lastname: Boniol
authors.forename: T
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authors.lastname: Zheng
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: M
authors.initials: M
authors.lastname: Pasterk
authors.forename: M
authors.initials: M
authors.lastname: Smans
authors.forename: M P
authors.initials: MP
authors.lastname: Curado
authors.forename: P
authors.initials: P
authors.lastname: Mullie
authors.forename: S
authors.initials: S
authors.lastname: Gandini
authors.forename: M
authors.initials: M
authors.lastname: Bota
authors.forename: G B
authors.initials: GB
authors.lastname: Bolli
authors.forename: J
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authors.lastname: Rosenstock
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authors.lastname: Autier
mesh_terms: D015992:Body Mass Index; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000453:epidemiology*; D005260:Female; D006801:Humans; D018570:Risk Assessment; D012307:Risk Factors