title: Diabetes and breast cancer among women with BRCA1 and BRCA2 mutations.
abstract: BACKGROUND
  Hyperinsulinemia and the metabolic syndrome are both risk factors for breast cancer. It is not clear if diabetes is associated with the risk of breast cancer in women with a BRCA1 or BRCA2 mutation.
  
  
  METHODS
  The authors reviewed the medical histories of 6052 women with a BRCA1 or BRCA2 mutation, half of whom had been diagnosed with breast cancer. They estimated the odds ratio for breast cancer, given a self-report of diabetes. They then estimated the hazard ratio for a new diagnosis of diabetes associated with a history of breast cancer.
  
  
  RESULTS
  There was no excess of diabetes in the period before the diagnosis of breast cancer, compared with controls with no diagnosis of breast cancer. The risk of diabetes was doubled among BRCA carriers in the 15-year period after the diagnosis of breast cancer (relative risk, 2.0; 95% confidence interval [CI], 1.4-2.8; P = .0001), compared with carriers without cancer. The risk was particularly high for women with a body mass index (BMI) >25.0 kg/m(2) (odds ratio, 5.8; 95% CI, 4.0-8.6; P = .0001).
  
  
  CONCLUSIONS
  After a diagnosis of breast cancer, women with a BRCA1 or BRCA2 mutation face a 2-fold increase in the risk of diabetes, which is exacerbated by a high BMI.
authors.affiliation: Juravinski Cancer Centre, Hamilton, Ontario, Canada.
authors.forename: Louise
authors.initials: L
authors.lastname: Bordeleau
authors.forename: Lorraine
authors.initials: L
authors.lastname: Lipscombe
authors.forename: Jan
authors.initials: J
authors.lastname: Lubinski
authors.forename: Parviz
authors.initials: P
authors.lastname: Ghadirian
authors.forename: William D
authors.initials: WD
authors.lastname: Foulkes
authors.forename: Susan
authors.initials: S
authors.lastname: Neuhausen
authors.forename: Peter
authors.initials: P
authors.lastname: Ainsworth
authors.forename: Michael
authors.initials: M
authors.lastname: Pollak
authors.forename: Ping
authors.initials: P
authors.lastname: Sun
authors.forename: Steven A
authors.initials: SA
authors.lastname: Narod
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000009:adverse effects; D001943:Breast Neoplasms / Q000150:complications* / Q000188:drug therapy / Q000235:genetics*; D016022:Case-Control Studies; D003920:Diabetes Mellitus / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D019398:Genes, BRCA1; D024522:Genes, BRCA2; D020022:Genetic Predisposition to Disease; D006801:Humans; D008875:Middle Aged; D009154:Mutation; D018570:Risk Assessment; D012307:Risk Factors
chemical_list: D000970:Antineoplastic Agents