Table 3.

Associations between vitamin D biomarkers and colorectal cancer risk by time since blood draw, African American participants of the SCCS

Time between blood draw and cancer diagnosis
≤3 years>3 years
BiomarkerCasesORa (95% CI)PtrendCasesORa (95% CI)Ptrend
25(OH)D, ng/mL
 Tertile 1: ≤10.49221 (Ref)491 (Ref)
 Tertile 2: 10.50–16.08281.22 (0.62–2.38)190.36 (0.19–0.69)
 Tertile 3: >16.08321.45 (0.75–2.79)250.45 (0.25–0.83)
 Per SD increase0.98 (0.76–1.28)0.900.69 (0.21–0.93)0.02
VDBP, μg/mL
 Tertile 1: ≤280.20241 (Ref)501 (Ref)
 Tertile 2: 280.21–320.00251.08 (0.57–2.03)440.91 (0.56–1.48)
 Tertile 3: >320.00381.55 (0.86–2.82)430.85 (0.52–1.38)
 Per SD increase1.26 (1.00–1.60)0.050.89 (0.72–1.10)0.27
Free 25(OH)Db
 Tertile 1: ≤5.02201 (Ref)401 (Ref)
 Tertile 2: 5.03–7.77291.38 (0.71–2.71)280.60 (0.33–1.09)
 Tertile 3: >7.77331.64 (0.83–3.23)250.51 (0.27–0.95)
 Per SD increase0.96 (0.74–1.25)0.760.71 (0.53–0.97)0.03
  • Abbreviations: 25(OH)D, 25-hydroxyvitamin D; VDBP, vitamin D–binding protein; Ref, reference; SD, standard deviation.

  • aAnalyses result from conditional logistic regression models where cases and controls are matched on age, race, and sex. Analyses are adjusted for calendar week of sample collection, body mass index, education, smoking, physical activity, alcohol intake, history of colorectal cancer screening, and family history of colorectal cancer.

  • bFree vitamin D biomarker is calculated as 25(OH)D:VDBP molar ratio (x103) and is a proxy for free 25-hydroxyvitamin D status.