Vitamin D and prostate cancer prognosis: a Mendelian randomization study

Purpose Decreased vitamin D levels have been associated with prostate cancer, but it is unclear whether this association is causal. A functional single-nucleotide polymorphism (SNP) in the group-specific component (GC) gene (T > G, rs2282679) has been associated with 25-hydroxy (25-OH) vitamin D and 1.25 dihydroxy (1.25-OH2) vitamin D levels. Methods To examine the hypothesized inverse relationship between vitamin D status and prostate cancer, we studied the association between this SNP and prostate cancer outcome in the prospective PROCAGENE study comprising 702 prostate cancer patients with a median follow-up of 82 months. Results GC rs2282679 genotypes were not associated with biochemical recurrence [hazard ratios (HR) 0.91, 95 % confidence interval (CI) 0.73–1.12; p = 0.36], development of metastases (HR 1.20, 95 % CI 0.88–1.63; p = 0.25) or overall survival (HR 1.10; 95 % CI 0.84–1.43; p = 0.50). Conclusions A causal role of vitamin D status, as reflected by GC rs2282679 genotype, in disease progression and mortality in prostate cancer patients is unlikely.