A higher circulating concentration of 25-hydroxyvitamin-D decreases the risk of renal cell carcinoma: a case-control study

OBJECTIVE: To investigate the relationship between vitamin D status, using circulating 25-hydroxyvitamin D [25 (OH) D], and renal cell carcinoma (RCC) risk in a case-control study, because the association between the two is unclear in China. MATERIALS AND METHODS: A total of 135 incident RCC cases were matched with 135 controls by age and sex. The blood samples were collected on the first day of hospitalization before surgery to measure plasma 25 (OH) D. Logistic regression analyses were used to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs) with adjustment for several confounders (e.g. age, gender, smoking and season of blood draw). Furthermore, the association of RCC with 25 (OH) D in units of 10 ng / mL as a continuous variable were also examined. RESULTS: The average plasma 25 (OH) D concentrations in RCC were significantly lower compared with those of the controls (21.5 ± 7.4 ng / mL vs. 24.1 ± 6.6 ng / mL, respectively; P = 0.003). In the adjusted model, inverse associations were observed between circulating 25 (OH) D levels and RCC risk for 25 (OH) D insufficiency (20-30 ng / mL) with OR of 0.50 (95% CI: 0.29-0.88; P = 0.015) and a normal 25 (OH) D level (≥ 30 ng / mL) with OR of 0.30 (95% CI: 0.13-0.72; P = 0.007), compared with 25 (OH) D deficiency (< 20 ng / mL). Furthermore, results with 25 (OH) D as a linear variable indicated that each 10 ng / mL increment of plasma 25 (OH) D corresponded to a 12% decrease in RCC risk. CONCLUSIONS: This case-control study on a Chinese Han population supports the protective effect of a higher circulating concentration of 25 (OH) against RCC, whether the confounding factors are adjusted or not.