title: Serum 25(OH) vitamin D and risk of breast cancer: a nested case-control study from the French E3N cohort.
abstract: BACKGROUND
  High 25-hydroxyvitamin D [25(OH)D] serum concentrations have been found to be associated with reduced breast cancer risk. However, few studies have further investigated this relationship according to menopausal status, nor have they taken into account factors known to influence vitamin D status, such as dietary and serum calcium, parathyroid hormone, and estradiol serum levels.
  
  
  METHODS
  We designed a nested case-control study within the French E3N cohort. Cases were women diagnosed with incident breast cancer (n = 636). Controls (n = 1,272) were matched with cases on age, menopausal status at blood collection, age at menopause, and center and year of blood collection. Multivariate logistic regression models were established.
  
  
  RESULTS
  We found a decreased risk of breast cancer with increasing 25(OH) vitamin D(3) serum concentrations (odds ratio, 0.73; 95% confidence interval, 0.55-0.96; P trend = 0.02) among women in the highest tertile. We also observed a significant inverse association restricted to women under 53 years of age at blood sampling [odds ratio (T(3) versus T(1)), 0.60; 95% confidence interval, 0.37-0.98; P trend = 0.04]. In premenopausal women, the risk was also decreased, although not significantly.
  
  
  CONCLUSIONS
  Our findings support a decreased risk of breast cancer associated with high 25(OH) vitamin D(3) serum concentrations, especially in younger women, although we were unable to confirm a direct influence of age or menopausal status.
  
  
  CONCLUSIONS
  Randomized intervention trials with vitamin D supplementation are required to confirm its benefits on breast cancer risk, but the maintenance of adequate vitamin D levels should be encouraged by public health policy.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale U1018, Center for Research in Epidemiology and Population Health, Université Paris-Sud, Villejuif Cedex, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Engel
authors.forename: Guy
authors.initials: G
authors.lastname: Fagherazzi
authors.forename: Anne
authors.initials: A
authors.lastname: Boutten
authors.forename: Thierry
authors.initials: T
authors.lastname: Dupré
authors.forename: Sylvie
authors.initials: S
authors.lastname: Mesrine
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Boutron-Ruault
authors.forename: Françoise
authors.initials: F
authors.lastname: Clavel-Chapelon
mesh_terms: D000367:Age Factors; D014408:Biomarkers, Tumor / Q000097:blood*; D001943:Breast Neoplasms / Q000097:blood* / Q000453:epidemiology; D002112:Calcifediol / Q000097:blood*; D002118:Calcium / Q000097:blood; D016022:Case-Control Studies; D015331:Cohort Studies; D004958:Estradiol / Q000097:blood; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D011374:Progesterone / Q000097:blood; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D014408:Biomarkers, Tumor; D010281:Parathyroid Hormone; D011374:Progesterone; D004958:Estradiol; D002112:Calcifediol; D002118:Calcium