Plasma vitamins E and A and risk of bladder cancer: a case-control analysis

Objective: Current results on the association between serum micronutrients and bladder cancer risk have been inconsistent. We assessed plasma vitamin E (alpha-tocopherol, and gamma-tocopherol), vitamin A (retinol), and bladder cancer risk using data collected from a case-control study. Methods: Epidemiologic data were collected via in-person interview. Plasma concentrations of alpha-tocopherol, gamma-tocopherol, and retinol were determined by a high-performance liquid chromatography assay. Multivariate logistic regression analyses were used to estimate bladder cancer risk in association with plasma vitamins E and A. Results: 386 bladder cancer patients and 389 age-, gender-, and ethnicity-matched controls were included in the study. The mean plasma alpha-tocopherol and retinol were significantly lower in cases than in controls (alpha-tocopherol: 23.93 mu g/ml vs. 27.48 mu g/ml, P < 0.001; retinol: 1.41 mu g/ml vs. 1.53 mu g/ml, P < 0.001). There was a significant reduction in bladder cancer risk associated with increasing plasma alpha-tocopherol level (Adjusted OR: 0.91; 95% CI: 0.85-0.97). In quartile analysis, using subjects with the lowest alpha-tocopherol level as the reference group, the adjusted ORs and 95% CIs for the second, third, and fourth quartiles were 0.75 (0.50-1.14), 0.69 (0.46-1.05), and 0.50 (0.32-0.78), respectively (P for trend = 0.003). Increased retinol level was also associated with reduced risk with OR of 0.57 (95% CI: 0.40-0.81). The ORs and 95% CIs for the second, third, and fourth quartiles were 0.92 (0.61-1.39), 0.66 (0.43-1.01), and 0.62 (0.40-0.95), respectively, with significant dose-response trend (P for trend = 0.01). Finally, there were significant correlations between plasma levels and dietary intakes for the three micronutrients. Conclusion: Our results suggest potential protective effect of alpha-tocopherol and retinol on bladder cancer risk. Future large prospective studies are needed to confirm the findings.