title: Association between low levels of 1,25-dihydroxyvitamin D and breast cancer risk.
abstract: OBJECTIVE
  To determine if blood levels of 25-hydroxyvitamin D (25-D) or its active metabolite, 1,25-dihydroxyvitamin D (1,25-D), are lower in women at the time of first diagnosis of breast cancer than in comparable women without breast cancer.
  
  
  METHODS
  This was a clinic-based case-control study with controls frequency-matched to cases on race, age, clinic and month of blood drawing.
  
  
  METHODS
  University-based breast referral clinics.
  
  
  METHODS
  One hundred and fifty-six women with histologically documented adenocarcinoma of the breast and 184 breast clinic controls.
  
  
  RESULTS
  There were significant mean differences in 1,25-D levels (pmol ml(-1)) between breast cancer cases and controls; white cases had lower 1,25-D levels than white controls (mean difference +/-SE: -11.08+/-0.76), and black cases had higher 1.25-D levels than black controls (mean difference +/-SE: 4.54+/-2.14), although the number of black women in the study was small. After adjustment for age, assay batch, month of blood draw, clinic and sample storage time, the odds ratio (95% confidence interval, CI) for lowest relative to highest quartile was 5.2 (95% CI 2.1, 12.8) for white cases and controls. The association in white women was stronger in women above the median age of 54 than in younger women, 4.7 (95% CI 2.1, 10.2) vs. 1.5 (95% CI 0.7, 3.0). There were no case-control differences in 25-D levels in either group.
  
  
  CONCLUSIONS
  These data are consistent with a protective effect of 1,25-D for breast cancer in white women.
authors.affiliation: Department of Epidemiology, University of North Carolina at Chapel Hill, 27599, USA. esther_janowsky@unc.edu
authors.forename: E C
authors.initials: EC
authors.lastname: Janowsky
authors.forename: G E
authors.initials: GE
authors.lastname: Lester
authors.forename: C R
authors.initials: CR
authors.lastname: Weinberg
authors.forename: R C
authors.initials: RC
authors.lastname: Millikan
authors.forename: J M
authors.initials: JM
authors.lastname: Schildkraut
authors.forename: P A
authors.initials: PA
authors.lastname: Garrett
authors.forename: B S
authors.initials: BS
authors.lastname: Hulka
mesh_terms: D000230:Adenocarcinoma / Q000097:blood*; D000328:Adult; D000704:Analysis of Variance; D001943:Breast Neoplasms / Q000097:blood*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D016017:Odds Ratio; D011863:Radioimmunoassay; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D