Association among plasma 1,25(OH)2D, ratio of 1,25(OH)2D to 25(OH)D, and prostate cancer aggressiveness
Background: African-American (AA) men tend to present with more aggressive prostate cancer (Gleason score >7) than European-American (EA) men. Vitamin D and its metabolites are implicated in prostate cancer biology with vitamin D deficiency, indicated by its metabolite levels in serum or plasma, usually observed in AA men. Objective: To determine if 1, 25-dihydroxy vitamin D3 [1,25(OH)2D] plasma levels in AA and EA prostate cancer patients alter the risk of having aggressive prostate cancer. Design: Research subjects from the North Carolina-Louisiana Prostate Cancer Project (AA n = 435 and EA n = 532) were included. Plasma metabolites 1,25(OH)2D and 25-hydroxyvitamin D3 [25(OH)D] were measured using liquid chromatography with tandem mass spectrophotometry. Research subjects were classified into low (Gleason sum < 7, stage T1-T2, and Prostate-specific antigen (PSA) < 9 ng/mL) or high (Gleason sum > 8 or Gleason sum = 7 with 4 + 3, or PSA > 20 ng/mL, or Gleason sum = 7 and stage T3-T4) aggressive disease. Results: Research subjects in the second and third tertiles of plasma levels of 1, 25(OH)2D had lower odds of high aggressive prostate cancer (AA [ORT2vsT1: 0.66, 95%CI: 0.39-1.12; ORT3vsT1: 0.83, 95%CI: 0.49-1.41] and EA [ORT2vsT1: 0.68, 95%CI: 0.41-1.11; ORT3vsT1: 0.67, 95%CI: 0.40-1.11]) compared with the first tertile, though confidence intervals included the null. Greater 1,25(OH)2D/25(OH)D molar ratios were associated with lower odds of high aggressive prostate cancer more evidently in AA (ORQ4vsQ1: 0.45, CI: 0.24-0.82) than in EA (ORQ4vsQ1: 0.64, CI: 0.35-1.17) research subjects. Conclusions: The 1,25(OH)2D/25(OH)D molar ratio was associated with decreased risk of high aggressive prostate cancer in AA men, and possibly in EA men. Further studies analyzing vitamin D polymorphisms, vitamin D binding protein levels, and prostatic levels of these metabolites may be useful. These studies may provide a better understanding of the vitamin D pathway and its biological role underlying health disparities in prostate cancer.
Ramakrishnan, S., Steck, S., Arab, L., Zhang, H., Bensen, J., Fontham, E., Johnson, C., Mohler, J., Smith, G., Su, L., & Woloszynska, A. (2019). Association among plasma 1,25(OH)2D, ratio of 1,25(OH)2D to 25(OH)D, and prostate cancer aggressiveness. Prostate, 79 (10), 1117-1124. https://doi.org/10.1002/pros.23824