Effect of selenium on virally induced and transplantable tumor models.

Se is effective in inhibiting both virally induced and transplantable tumors. Continued intake of Se at quantities greater than those required to optimize growth and glutathione peroxidase (EC 1.11.1.9) activities appear to be needed to achieve maximal tumor inhibition. Differences in the sensitivity to Se of various tumor cell lines are evident. The efficacy of Se depends on the form and mode of administration of this trace element. Total tumor mass also appears to affect the efficacy of Se. Evidence now suggests that selenodiglutathione or some other intermediate in Se metabolism is responsible for the antitumorigenic properties of this trace element.