Vitamin D-Binding Protein and Risk of Renal Cell Carcinoma in the Cancer Prevention Study-II Cohort

Background: Kidney cancer has several well-established risk factors, including smoking, obesity, and hypertension. These factors do not, however, completely account for its etiology. One previous study of vitamin D-binding protein (DBP) and risk of renal cell carcinoma found a striking inverse association that warranted replication. Methods: We conducted a nested case-control study in the American Cancer Society Cancer Prevention Study-II Nutrition Cohort to prospectively examine circulating DBP concentration and renal cell carcinoma risk. Cases (n = 87) were matched 1:1 to controls on gender, race, age (+/-5 years), and date of blood collection (+/-30 days). ORs and 95% confidence intervals (CIs) were estimated for quartiles of DBP using conditional logistic regression. Results: There was a statistically significant inverse trend across quartiles of DBP such that participants with higher DBP had a markedly decreased risk of renal cell carcinoma (vs. Q1: Q2 OR, 0.93; 95% CI, 0.41-2.11; Q3 OR, 0.42; 95% CI, 0.15-1.15; Q4 OR, 0.33; 95% CI, 0.10-1.06; P-trend = 0.03). Conclusions: Our findings demonstrate a strong inverse association between circulating DBP and risk of renal cell carcinoma, supporting the findings from previous research. Impact: This is only the second study to examine DBP and risk of kidney cancer, and one of only a handful of studies to examine circulating DBP and risk of cancer at any site. Our findings support emerging evidence for an etiologic role of DBP in cancer and may provide insights into the etiology of kidney and other cancers. (C) 2018 AACR.