NIH Research Festival
Background: Prospective studies involving predominately non-Hispanic white men suggest higher vitamin D status may increase prostate cancer risk. Although black race is a well-established risk factor for both low vitamin D status and prostate cancer, little is known about the role of vitamin D in the etiology of prostate cancer in black men. We prospectively examined the association between vitamin D and prostate cancer risk among non-Hispanic black men in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Methods: We identified 226 prostate cancer cases and 452 controls matched on age at randomization, date of blood draw, calendar year of study entry, and time since baseline prostate cancer screening. Conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association between serum 25-hydroxyvitamin D (25(OH)D), vitamin D binding protein (DBP), their molar ratio (25(OH)D:DBP) and prostate cancer risk. Results: Higher serum 25(OH)D was not significantly associated with prostate cancer overall (Q4 vs. Q1 OR=0.73, 95% CI:0.40-1.33, P for trend=0.25), although it appeared inversely associated with risk in older men (P for interaction=0.04) and for non-aggressive disease (global P = 0.03). Serum DBP was significantly inversely associated with risk (Q4 vs. Q1 OR=0.45, 95% CI: 0.20-1.00, P for trend=0.03), whereas the 25(OH)D:DBP molar ratio was not. Results were similar when we mutually adjusted for 25(OH)D and DBP, and we found no evidence of interaction between the two. Conclusion: Higher circulating DBP appears independently associated with lower prostate cancer risk in black men.
Scientific Focus Area: Health Disparities
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