Exposure to selenium and risk of cutaneous melanoma

Selenium (Se) is a metalloid of strong toxicological and nutritional interest in human health, and both beneficial and adverse effects on the risk of human cancer have been suggested on the basis of epidemiologic and laboratory studies. A recent trial has shown no beneficial effects of Se on cancer risk, and two prospective studies indicated an excess incidence of melanoma among subjects with the highest Se exposure. We investigated this possible association through a population-based case-control study in an Italian community.Fifty-nine patients with newly-diagnosed cutaneous melanoma and fifty-nine population controls residing in the city of Modena, northern Italy, reported details about their life-style and dietary habits and yielded a blood sample. We assessed serum Se concentrations through atomic absorption spectrometry, and we calculated the relative risk (RR) of melanoma with its 95% confidence interval (CI) associated with serum Se concentrations through conditional and unconditional logistic regression models, adjusting for potential confounders.RR of melanoma was increased in the middle tertile (2.2, 95% CI 0.7-6.9) and in the upper tertile (4.4, 95% CI 1.5-12.6) of serum Se levels, as compared to subjects in the bottom tertile, with P for linear trend of 0.001. These results were substantially confirmed after adjustment for potential confounders such as family history of melanoma, number of atypical nevi, sun exposure, history of sunburns, and education. Serum Se levels were associated to dietary intake of Se, as evaluated through a semi-quantitative food frequency questionnaire, in patients but not in controls.In this population, disease risk was strongly associated with a biological indicator of Se exposure, serum Se concentration, though risk estimates were statistically unstable due to the small sample size. Study findings appear to confirm that exposure to environmental Se increases the risk of cutaneous melanoma.