This study investigated the therapeutic effect of combining methylselenocysteine (a bioavailable form of selenium) with tamoxifen on estrogen receptor alpha positive breast cancer tumors implanted in female nude mice. MCF-7 breast cancer xenografts were established in ovariectomized nude mice who were then treated with either tamoxifen, methylselenocysteine, or a combination of the two. Treatment with both tamoxifen and methylselenocysteine synergistically inhibited the growth of tumors compared to tamoxifen alone or methylselenocysteine alone. Methylselenocysteine alone and methylselenocysteine plus tamoxifen significantly reduced ERα while increasing cell death in breast cancer cells. The authors conclude that selenium may provide an added benefit when combined with tamoxifen in adjuvant therapy or prevention.
Selenium and breast cancer treatment
The study findings confirm those of previous studies which found that selenium enhances the action of tamoxifen in tamoxifen-sensitive and tamoxifen-resistant breast cancer cells. The following foods are sources of selenium in the diet while also protecting against breast cancer:
Black pepper has been found to increase the bioavailability of selenium in the diet. We do not recommend selenium supplements. Selenium can be toxic if overconsumed.