A study published online in Biochemistry on January 24, 2011 suggests that not all forms of selenium are equally affective in preventing cancer.The efficacy of selenium has been studied. The Nutritional Prevention of Cancer clinical trial showed selenium reduced the cancer risk while the Selenium and Vitamin E Cancer Prevention Trial did not, according to Hugh Harris of the University of Adelaide in Australia and colleagues who conducted the current study.Harris et al. tested two forms of selenium, selenomethionine (SeMet) and Se-methylselenocysteine (MeSeCys),  on lung cancer cells and found the latter killed more lung cancer cells than the former did.They also found lung cancer cells treated with MeSeCys processed selenium differently than cells treated with SeMet, which the researchers said explains why the results of trials are inconsistent.David Liu