SELENIUM AND CANCER

Selenium biochemistry is complex. It is consumed in many forms and at different absorption levels, being used in combination with many different proteins in the body. Each form has its own unique set of abilities. The three forms of selenium most important in cancer prevention are sodium selenite, L-selenomethionine, and selenium-methyl L-selenocysteine.

Possibly the most active is inorganic sodium selenite  which has been shown to kill cancer cells in more than 8 studies (For example, Fu L, Liu Q, Shen L, Wang Y. Proteomic study on sodium selenite-induced apoptosis of human cervical cancer HeLa cells. J Trace Elem Med Biol. 2011 Jul;25(3):130-7; or, Dziaman T, Huzarski T, Gackowski D, et al. Selenium supplementation reduced oxidative DNA damage in adnexectomized BRCA1 mutations carriers. Cancer Epidemiol Biomarkers Prev. 2009 Nov;18(11):2923-8; or, Ma Q, Fang H, Shang W, et al. Superoxide flashes: early mitochondrial signals for oxidative stress-induced apoptosis. J Biol Chem. 2011 Aug 5;286(31):27573-81.).
In particular, it seems capable of generating forms of radical ´oxygen´ molecules that kill off the types of mitochondria that only exist in cancer cells. There is a protein in cancer cells Bcl-2 that stops apoptosis - the cell killing itself. Selenium seems to block this action.
It also increases the activity of the antioxidant enzyme glutathione peroxidase in healthy tissue, so promoting a double action - killing the cancer cells and protecting the healthy ones. It helps repair damaged DNA and enhances the immune system
The above actions all suggest a role as a complementary therapy in your cancer treatment programme.
But selenium is important in prevention too: In early 2009 German scientists from St. Josef´s Hospital in Wiesbaden presented their findings on selenium, concluding that selenium blood levels were significantly lower in men with benign prostate hypertrophy or prostate cancer. (Acta Oncologica)
In another study (Molecular Nutrition and Food Research, 2009) experts suggest selenoproteins have powerful antioxidative and anti-inflammatory effects that could make them important in preventing prostate and colorectal  cancers.
In the March 2009 edition of Clinical Cancer Research researchers from Penn State College of Medicine showed that isothiocyanates found in cruciferous vegetables (like cabbage, cauliflower and kale) when combined with selenium supplementation became even more potent in treating melanoma.
´Selenium deficiency is common in cancer patients, including those diagnosed with metastatic cancer´, said lead researcher Professor Gavin Robertson.
Importantly, in the prostate cancer studies and in the melanoma research, it was found that a protein, Akt3, develops and this is driven by oestrogen, There are no drugs to stop it, and Akt3 causes the cancer to develop, according to Robertson. ´Selenium is known to destabilise Akt3´, he adds.
Finally, in 2012 (American Journal of Clinical Nutrition; 2012 Jul;96 (1) 111-22) scientists from the Department of Nutrition at Norwich Medical School studied the effects of selenium in preventing prostate cancer. Their meta-analysis of randomized controlled trials, case-control studies, and prospective cohort studies reviewed studies on blood plasma levels: Twelve studies with a total of 13,254 participants and 5007 cases of prostate cancer were included. The relation between plasma/serum selenium and prostate showed that the risk decreased with increasing plasma/serum selenium up to 170 ng/mL.