Circulating 25-hydroxyvitamin D₃ in relation to renal cell carcinoma incidence and survival in the EPIC cohort

Normal renal function is essential for vitamin D metabolism, but it is unclear whether circulating vitamin D is associated with risk of renal cell carcinoma (RCC). We assessed whether 25-hydroxyvitamin D₃ (25(OH)D₃) was associated with risk of RCC and death after RCC diagnosis in the European Prospective Investigation into Cancer and Nutrition (EPIC). EPIC recruited 385,747 participants with blood samples between 1992 and 2000. The current study included 560 RCC cases, 557 individually matched controls, and 553 additional controls. Circulating 25(OH)D₃ was assessed by mass spectrometry. Conditional and unconditional logistic regression models were used to calculate odds ratios and 95% confidence intervals. Death after RCC diagnosis was assessed using Cox proportional hazards models and flexible parametric survival models. A doubling of 25(OH)D₃ was associated with 28% lower odds of RCC after adjustment for season of and age at blood collection, sex, and country of recruitment (odds ratio = 0.72, 95% confidence interval: 0.60, 0.86; P = 0.0004). This estimatewas attenuated somewhat after additional adjustment for smoking status at baseline, circulating cotinine, body mass index (weight (kg)/height (m)²), and alcohol intake (odds ratio = 0.82, 95% confidence interval: 0.68, 0.99; P = 0.038). There was also some indication that both low and high 25(OH)D₃ levels were associated with higher risk of death from any cause among RCC cases.