Treatment of well differentiated thyroid tumors (WDTC) is based on surgery followed by treatment with radioactive iodine (RAI) for the ablation of possible remnants and/or metastases. The success of RAI therapy can be due, essentially to the presence and functionality of the sodium iodine symporter (NIS) in the tumor cell membrane. In The majority of the WDTC maintain the expression and functionality of NIS, which allows the incorporation of radioactive iodine (131I) into the tumor cells, leading to its death.