Table 3.

Summary incidence rate ratios (RR) of colorectal cancer according to vitamin D status and functional vitamin D–binding protein (DBP) isoforms in the EPIC, CPS-II, and NHS cohorts

	DBP1-1 (rs4588 CC)†				DBP1-2 or DBP2-2 (rs4588 CA or AA)‡
25(OH)D concentration (IOM-defined vitamin D status)*	No. cases	No. controls	RR (95% CI)§	P trend	No. cases	No. controls	RR (95% CI)§	P trend	P heterogeneity by DBP2
< 30 nmol/L (deficient)*	144	104	1.00 (Referent)		218	107	1.00 (Referent)
30 to < 50 nmol/L (insufficient)	386	267	1.20 (0.86 to 1.67)		320	285	0.69 (0.51 to 0.95)		.02
50 to < 75 nmol/L (sufficient)	266	288	0.92 (0.63 to 1.34)		191	266	0.44 (0.27 to 0.73)		.02
≥ 75 nmol/L (beyond sufficient)	105	196	0.66 (0.37 to 1.16)	0.01	80	136	0.40 (0.23 to 0.68)	5.8 × 10−5	.21
< 30 nmol/L (deficient)	144	104	1.00 (Referent)		218	107	1.00 (Referent)
30 to < 50 nmol/L (insufficient)	386	267	1.19 (0.85 to 1.66)		320	285	0.69 (0.50 to 0.94)		.02
≥ 50 nmol/L (sufficient)	371	484	0.88 (0.61 to 1.27)	0.09	271	402	0.47 (0.33 to 0.67)	.0001	.01
< 50 nmol/L (nonsufficient)	530	371	1.00 (Referent)		538	392	1.00 (Referent)
≥ 50 nmol/L (sufficient)	371	484	0.79 (0.63 to 1.00)		271	402	0.60 (0.47 to 0.76)		.10

25(OH)D = 25-hydroxyvitamin D; CI = confidence interval; CPS-II = Cancer Prevention Study-II; DBP = vitamin D–binding protein; EPIC = European Prospective Investigation into Cancer and Nutrition; IOM = Institute of Medicine; NHS = Nurses’ Health Study; RR = incidence rate ratio.

^*The 25(OH)D blood concentrations were calibrated to the same assay and seasonally adjusted using the method described by Gail et al. (21).

^†Participants with no minor allele at GC-rs4588 (rs4588*CC genotype) were defined as not having the DBP2 isoform (or only DBP1 isoforms).

^‡Participants with a minor allele at GC-rs4588 (rs4588*CA or rs4588*AA genotypes) were defined as having the DBP2 isoform.