PRDX5 and neoplasm: 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.