Abstract： To the Editor:Thyroid cancer,which is one of the most common diseases of the endocrine system,can be divided into four primary types,including papillary thyroid cancer (PTC) accounting for 80％ to 90％ of cases,follicular thyroid cancer accounting for 10％ to 15％ of cases,medullary thyroid cancer (MTC) accounting for 3％ to 10 ％ of cases,and anaplastic thyroid cancer accounting for 1％ to 2％ of cases.