Abstract
BACKGROUND: Epidemiologic studies have shown that men with type II diabetes have a lower risk of prostate cancer than non-diabetic men. Recently, common variants in two genes, HNF1B and JAZF1, were found to be associated with both of these diseases. METHODS: We examined whether the relationship between HNF1B and JAZF1 variants and decreased prostate cancer risk may potentially be mediated through diabetes in two large prospective studies, the Cancer Prevention Study II Nutrition Cohort and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. RESULTS: Three HNF1B SNPS, rs11649743, rs4430796, and rs7501939, were associated with decreased risk of prostate cancer and were also associated, with marginal statistical significance, with increased risk of diabetes. The JAZF1 SNPs rs6968704 and rs10486567 were associated with decreased risk of prostate cancer but were not associated with diabetes. All five SNP-prostate cancer relationships did not substantially differ when the analyses were stratified by diabetic status or when diabetic status was controlled for in the model. Furthermore, the association of diabetes with prostate cancer was not altered when the SNPs were included in the logistic model. CONCLUSIONS: These findings indicate that the HNF1B variants are directly associated with both diabetes and prostate cancer, that diabetes does not mediate these gene variant-prostate cancer relationships, and the relationship between these diseases is not mediated through these gene variants.