Table 5.

Association between plasma 25(OH)D stratified by VDBP, and between VDBP stratified by 25(OH)D, and risk of colorectal cancer in the Nurses' Health Study (1990–2011)

AnalysisQuartile 1Quartile 2Quartile 3Quartile 4P for trendP for interactiona
Total 25(OH)D
 Low VDBPb
  No. of cases/controls65/9262/9139/8828/73
  Multivariable OR (95% CI)c1 (referent)0.96 (0.59–1.55)0.62 (0.37–1.05)0.57 (0.32–1.02)0.010.34
 High VDBPb
  No. of cases/controls50/8043/8147/8344/101
  Multivariable OR (95% CI)c1 (referent)0.84 (0.49–1.46)0.84 (0.49–1.46)0.84 (0.49–1.46)0.19
Free 25(OH)D
 Low VDBPb
  No. of cases/controls35/4139/6348/9772/144
  Multivariable OR (95% CI)c1 (referent)0.70 (0.38–1.29)0.49 (0.27–0.91)0.57 (0.32–1.00)0.150.79
 High VDBPb
  No. of cases/controls83/13153/11032/7416/29
  Multivariable OR (95% CI)c1 (referent)0.74 (0.47–1.17)0.71 (0.43–1.20)0.88 (0.43–1.77)0.2
Bioavailable 25(OH)D
 Low VDBPb
  No. of cases/controls29/4839/5745/9481/146
  Multivariable OR (95% CI)c1 (referent)1.21 (0.64–2.30)0.74 (0.39–1.38)0.97 (0.55–1.72)0.870.73
 High VDBPb
  No. of cases/controls76/12451/11638/7819/26
  Multivariable OR (95% CI)c1 (referent)0.67 (0.41–1.09)0.85 (0.50–1.43)1.27 (0.63–2.54)0.77
VDBP-bound 25(OH)D
 Low VDBPb
  No. of cases/controls76/10659/9140/8119/67
  Multivariable OR (95% CI)c1 (referent)0.88 (0.55–1.39)0.69 (0.42–1.13)0.41 (0.22–0.76)0.0070.33
 High VDBPb
  No. of cases/controls46/6738/8053/9247/105
  Multivariable OR (95% CI)c1 (referent)0.67 (0.38–1.19)0.82 (0.48–1.42)0.59 (0.33–1.06)0.14
VDBP
 Low total 25(OH)Db
  No. of cases/controls71/9956/8447/9046/71
  Multivariable OR (95% CI)c1 (referent)1.00 (0.62–1.62)0.83 (0.51–1.35)0.95 (0.57–1.57)0.460.79
 High total 25(OH)Db
  No. of cases/controls32/7335/8841/8250/102
  Multivariable OR (95% CI)c1 (referent)0.95 (0.53–1.72)1.12 (0.63–2.00)1.12 (0.64–1.96)0.50
  • aWald test was used for the product term between stratified variable (binary) and main exposure (continuous).

  • bLow level was defined as ≤median concentration among control participants [279 mg/mL for VDBP, 27.5 ng/mL for total 25(OH)D], and high level otherwise.

  • cConditional logistic regression adjusted for matching factors (age and time of blood draw), family history of colorectal cancer, multivitamin use, pack-years of smoking (0, 0–9.9, 10–24.9, 25–49.9, ≥50), alcohol consumption (0, 0–5.0, 5.1–15.0, >15 g/d), BMI (continuous), physical activity (≤5, 5.1–10, 10.1–20, >20 METs), regular aspirin/NSAID use, postmenopausal status and hormone use (premenopausal, never use of postmenopausal hormone, ever use of postmenopausal hormone), calcium intake (in quartiles), and Alternative Healthy Eating Index (in quartiles).