Influence of vitamin D binding protein on the association between circulating vitamin D and risk of bladder cancer

• Published in: British journal of cancer 2012-10, Vol.107 (9), p.1589-1594
• Main Authors: Mondul, A M, Weinstein, S J, Virtamo, J, Albanes, D
• Format: Article
• Language: English
• Subjects: 631/443/810; 631/67/2324; 692/699/67/589/1336; alpha-Tocopherol - therapeutic use; Anticarcinogenic Agents - therapeutic use; beta Carotene - therapeutic use; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Bladder cancer; Cancer Research; Case-Control Studies; Double-Blind Method; Drug Resistance; Epidemiology; Humans; Male; Medical sciences; Middle Aged; Molecular Medicine; Nephrology. Urinary tract diseases; Oncology; Prospective Studies; Risk Factors; Tumors; Tumors of the urinary system; Urinary Bladder Neoplasms - blood; Urinary Bladder Neoplasms - prevention & control; Urinary tract. Prostate gland; Vitamin D - analogs & derivatives; Vitamin D - blood; Vitamin D-Binding Protein - blood
• ISSN: 0007-0920; 1532-1827; 1532-1827
• DOI: 10.1038/bjc.2012.417

Background: There is little research investigating the role of vitamin D binding protein (DBP) in the association between 25-hydroxyvitamin D (25(OH)D) and disease risk. Methods: Within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, 250 bladder cancer cases were randomly sampled and matched 1:1 to controls on age and date of blood collection. Odds ratios (OR) and 95% confidence intervals (CI) of bladder cancer were estimated by quartiles of DBP (measured by ELISA), 25(OH)D and the molar ratio of 25(OH)D:DBP, a proxy for free circulating 25(OH)D. Analyses were also conducted stratifying 25(OH)D by DBP (median split) and vice versa. Results: We found no direct association between circulating DBP levels and bladder cancer risk ( P -trend=0.83). The inverse association between 25(OH)D and bladder cancer risk was unchanged after adjustment for DBP (Q4 vs Q1 OR=0.61, 95% CI=0.36–1.05; P -trend=0.04), and was stronger among men with lower DBP (low DBP: 25(OH)D Q4 vs Q1 OR=0.47, 95% CI=0.23–1.00; high DBP: 25(OH)D Q4 vs Q1 OR=0.83, 95% CI=0.40–1.75; P for interaction=0.11). Conclusion: Our findings provide additional support for an aetiologic role for vitamin D in bladder cancer and suggest that free, rather than total, circulating vitamin D may be a more relevant exposure when examining bladder and, perhaps, other cancers.