Abstract B81: Vitamin D and prostate cancer aggressiveness among African and European Americans in the North Carolina-Louisiana Prostate Cancer Project (PCaP) case study cohort
Authors: Woloszynska-Read Anna , Tian Lili , Mohler James L. , Fontham Elizabeth T. , Bensen Jeannette T. , Johnson Candace S. , Trump Donald L. 
Published: June 2012

25(OH) vitamin D3 [25D3] serum levels have been associated with increased risk and unfavorable outcomes in several types of cancer, including breast, bladder, lung, and colon cancer. The relationship between vitamin D and prostate cancer prognosis and outcome is less well-studied. This pilot study utilized 200 samples from the North Carolina-Louisiana Prostate Cancer Project (PCaP) cohort to investigate the association between circulating 25D3 levels and an aggressive phenotype of prostate cancer in 100 African American (AA) and 100 European American (EA) men.

Plasma vitamin D levels were categorized as deficient ≤20 ng/ml, insufficient ≤30 and &gt;20 ng/ml, and sufficient &gt;30ng/ml. The mean value of plasma vitamin D levels in the 200 research subjects was 24.7 ng/ml (STD 11.0, minimum value 6.3, and maximum value 62), which indicated vitamin D deficiency and insufficiency in a large portion of patients. AA men were more likely than EA men to present with vitamin D deficiency, which may be due to differences in skin pigmentation. As expected, significant (P &lt;.0001) differences in vitamin D serum levels were found between AA men (mean value of 20.9 ng/ml) and EA men (mean value of 28.4 ng/ml). AA men with prostate cancer often present with vitamin D deficiency.

Prostate tumor aggressiveness was categorized by PCaP as high, low, and intermediate, using clinical grade, clinical stage, and serum PSA at diagnosis [High aggressive: clinical stage ≥ T3 and Gleason grade ≥ 7 or Gleason sum ≥ 8 or PSA &gt; 20; Low: Gleason sum &lt; 7 and clinical stage ≤ T2 and PSA &lt; 10]. An equal number of high aggressive (100 cases) and low aggressive (100 cases) tumors were included in the analysis. We then analyzed the relationship between vitamin D serum levels and prostate cancer aggressiveness. There was no significant correlation between disease aggressiveness and plasma concentrations of vitamin D. However, a significant inverse relationship was found between vitamin D and PSA levels (P=.0008). A trend was observed in which vitamin D deficient (&lt;20ng/ml) AA men were diagnosed with more aggressive prostate cancer than AA men who were either vitamin D insufficient or sufficient. Specifically, out of 100 AA men with prostate cancer 59 were 25D3 deficient. Of these, over 50 percent had tumors classified as high aggressive. A similar trend was not observed among EA men. We controlled for season of blood collection: EA men had their lowest levels of circulating vitamin D during winter. Seasonal differences were not observed among AA men.

This pilot study will be extended to the entire PCaP cohort of 2256 men in order to confirm these observations. In addition, we will continue to investigate the role of diet and dietary supplements on vitamin D levels in the PCaP cohort. Further analyses will add racial admixture estimates into our models in order to correct for population stratification. This is necessary since self-identified race may or may not reflect ancestral origins accurately.

Acknowledgments: The authors thank the North Carolina Central Cancer Registry, the Louisiana Tumor Registry, and the PCaP staff, advisory committees and participants for their important contributions. The Prostate Cancer Project (PCaP) is carried out as a collaborative study supported by the Department of Defense contract DAMD 17-03-2-0052. AWR is supported by the Department of Defense grant W81WH11-1-0308 and R25CA113951-01 grant from the National Cancer Institute.

Citation Information: Cancer Epidemiol Biomarkers Prev 2011;20(10 Suppl):B81.