Prostate cancer (PC) chemoprevention has generated considerable interest in the last decade and selenium and combinations of selenium have been recognized as one of the most efficacious chemopreventive agents against PC. This review focuses on a discussion of the knowledge hitherto gained about the mechanisms of action of the various in vitro and in vivo used selenium compounds and their effects on cellular processes and signaling pathways. We also describe the clinical and preclinical studies that have contributed enormously to the knowledge about dose, duration of exposure, and the chemical form of selenium effective in different scenarios. Even though the jury is still out about whether selenium can be used as a chemopreventive agent in the clinic and whether studies with cell lines and populations at low, medium, or high risk can adequately represent the physiological behavior of this micronutrient, it can safely be said to offer the most diverse spectrum of protective effects against this particular type of cancer which may augur well for its future as a chemopreventive agent.
