Moreover, selenite is an essential trace element for the body to synthesize selenoproteins [30–33], and some studies shown that selenite within the nutritional range concentration can inhibit tumor formation [34–38], but in the over nutritional levels, selenite can induce endoplasmic reticulum stress, mitochondrial related apoptosis, DNA strand breaks and cell-cycle arrest [39–41], which suggests that selenite has potential therapeutic effects for cancer treatment [42–45]. The gene discussed is SELENOS; the disease is cancer.