The expression of NIS occurs in 80% to 90% of breast cancer cases and, thus, symporter could be potentially used in the radioisotope breast imaging with 125I (alternatively 99mTc) and in the breast cancer treatment with 131I (alternatively 188Re) [13], following administration of stimulants enhancing NIS expression [29,30]. The gene discussed is SLC5A5; the disease is breast carcinoma.