skin whitening using glutathione: What is glutathione and its purpose (Brand: Met-tathione)

I had just opened my second bottle of Met-tathione. While I am waiting for significant effect of glutathione on my skin, let me share you some information regarding glutathione. According to Wikipedia, glutathione is an antioxidant that protects cells from free radicals and peroxides. Free radicals and peroxides contribute to the aging and destruction of the cells in our body. Glutathione is actually being produced in our body. However, supplementation will only help a side effect, which is skin whitening. Furthermore, according to a website ( which I forgot already) and also stated in Wikipedia, glutathione products such as Met-tathione are actually anti-cancer drugs. They are given to cancer-stricken patients and can help alleviate the effects of cancer to the body. This makes me wonder if longer use of glutathione is safe because I wonder if it will make me invincible or vulnerable to cancer cells. Even so, since I am only taking what is required for skin whitening and maybe if my dark skin will become lighter, I think I will stop taking glutathione for the meantime.