Post SELECT: selenium on trial.

Selenium is an essential trace element for humans and other animals that is required in very small amounts for proper growth and functioning. Several selenium compounds have shown promise as cancer chemopreventive and chemotherapeutic agents. However, the negative outcome of the SELECT trial to some extent dampened the enthusiasm of selenium-related drug development. A look at the selenium compounds, their diverse mechanism of action, bioavailability and efficacy based on chemical structure, however, suggests that failure of SELECT that used selenomethionine supplement to prevent prostate cancer was not a failure of selenium compounds as a whole. This is certainly true in regard to therapeutic applications of selenium compounds. This article puts these arguments in perspective, and based on the literature reports, especially several newly developed selenium compounds, emphasizes the importance of selenium in the development of chemopreventive and particularly chemotherapeutic drugs for cancer in near future.