RET and medullary thyroid gland carcinoma: Taking data from the amplification-refractory mutation system (ARMS) assay into account, which specifically detects the most common RET variant, M918T, patients with sporadic MTC showed benefit from vandetanib treatment whether their tumors were RETM918T positive or negative; however, the response rate was greater in those who had the RETM918T variant [2].