Dietary cadmium intake and risk of prostate cancer: A Danish prospective cohort study

Background: Cadmium is classified as a human lung carcinogen based on evidence from high-exposure occupational settings. Though cadmium has no physiological role, increasing evidence suggests cadmium may mimic steroid hormones. This dual ability of being carcinogenic and hormone-like makes cadmium a concern for hormone-related cancers. Causes of prostate cancer are not clear, but steroid hormones, particularly androgens and probably estrogens, may be involved. Cadmium has been positively associated with prostate cancer in occupationally exposed men. In non-occupationally exposed populations, diet and smoking are the main sources of cadmium exposure. The aim of this study was to investigate the association between dietary cadmium intake and prostate cancer risk in Danish men. Methods: Dietary cadmium intake was estimated in the Danish Diet, Cancer and Health cohort at baseline 1993-97. The estimates were based on a 192 item semi-quantitative food frequency questionnaire and cadmium contents in all food items. Among 26,778 men we identified 1,567 prostate cancer cases from baseline through December 31, 2010 using the Danish Cancer Registry. The association between dietary cadmium intake and prostate cancer risk was analysed using Cox regression models. Results: We did not find an association between dietary cadmium intake and prostate cancer risk (adjusted incidence rate ratio per 10 μg day^-1 = 0.98 (95% CI = 0.88-1.10)). The association did not differ according to aggressiveness of prostate cancer. Educational level, smoking status, BMI, zinc or iron intake did not modify the association. Conclusions: In our study, we did not find an association between dietary cadmium intake and prostate cancer risk in a cohort of Danish men.