Serum Vitamin D, Vitamin D Binding Protein, and Risk of Colorectal CancerReport as inadecuate




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Background

We previously reported a positive association between serum 25-hydroxyvitamin D 25OHD and colorectal cancer risk. To further elucidate this association, we examined the molar ratio of 25OHD to vitamin D binding protein DBP, the primary 25OHD transport protein, and whether DBP modified the association between 25OHD and colorectal cancer risk.

Methods

In a nested case-control study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, controls were 1∶1 matched to 416 colorectal cancer cases based on age and date of blood collection. Logistic regression was used to estimate odds ratios ORs and 95% confidence intervals CI for quartiles of 25OHD, DBP, and the molar ratio of 25OHD:DBP, a proxy for free, unbound circulating 25OHD.

Results

Comparing highest to lowest quartiles, DBP was not associated with colorectal cancer risk OR = 0.91; 95% CI: 0.58, 1.42, p for trend  = 0.58; however, a positive risk association was observed for the molar ratio of 25OHD:DBP OR = 1.44; 95% CI: 0.92, 2.26, p for trend  = 0.04. In stratified analyses, the positive association between 25OHD and colorectal cancer was stronger among men with DBP levels above the median OR = 1.89; 95% CI: 1.07, 3.36, p for trend  = 0.01 than below the median OR = 1.20; 95% CI: 0.68, 2.12, p for trend  = 0.87, although the interaction was not statistically significant p for interaction  = 0.24.

Conclusion

Circulating DBP may influence the association between 25OHD and colorectal cancer in male smokers, with the suggestion of a stronger positive association in men with higher DBP concentrations. This finding should be examined in other populations, especially those that include women and non-smokers.



Author: Gabriella M. Anic , Stephanie J. Weinstein, Alison M. Mondul, Satu Männistö, Demetrius Albanes

Source: http://plos.srce.hr/



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