Data from Total and Free Circulating Vitamin D and Vitamin D–Binding Protein in Relation to Colorectal Cancer Risk in a Prospective Study of African Americans

Abstract

<div>Abstract<p><b>Background:</b> Previous studies rarely evaluated the associations between vitamin D–binding protein and free vitamin D with colorectal cancer risk. We assessed these biomarkers and total 25-hydroxyvitamin D in relation to colorectal cancer risk in a sample of African Americans.</p><p><b>Methods:</b> Cases comprised 224 African American participants of the Southern Community Cohort Study diagnosed with incident colorectal cancer. Controls (<i>N</i> = 440) were selected through incidence density sampling and matched to cases on age, sex, and race. Conditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI) for associations between biomarker levels and colorectal cancer risk.</p><p><b>Results:</b> Vitamin D was inversely associated with colorectal cancer risk where the OR per-SD increase in total and free 25-hydroxyvitamin D were 0.82 (95% CI, 0.66–1.02) and 0.82 (95% CI, 0.66–1.01), respectively. Associations were most apparent among cases diagnosed >3 years after blood draw: ORs for the highest tertile versus the lowest were 0.69 (95% CI, 0.21–0.93) for total 25-hydroxyvitamin D and 0.71 (95% CI, 0.53–0.97) for free 25-hydroxyvitamin D. Inverse associations were seen in strata defined by sex, BMI, and anatomic site, although not all findings were statistically significant. Vitamin D–binding protein was not associated with colorectal cancer risk.</p><p><b>Conclusions:</b> Our findings suggest that total and free 25-hydroxyvitamin D may be inversely associated with colorectal cancer risk among African Americans.</p><p><b>Impact:</b> These findings highlight a potential role for vitamin D in colorectal cancer prevention in African Americans. <i>Cancer Epidemiol Biomarkers Prev; 26(8); 1242–7. ©2017 AACR</i>.</p></div>