This may reflect a role for these selenoproteins in the progression of prostate cancers rather that initiation, especially in view of the reported relationship between thioredoxin reductase activity and tumour aggressiveness [29]; alternatively, there may be different etiologies for the localized, low grade and the advanced, high grade cancers with different roles for the selenoproteins in the two disease situations. The gene discussed is SELENOS; the disease is prostate cancer.