[The significance and latest progress of extrathyroidal extension of thyroid cancer].

Extrathyroidal extension of thyroid cancer has been an important adverse factor affecting the prognosis of patients. According to the latest NCCN (National Comprehensive Cancer Network) guidelines, extrathyroidal extension is the surgical guide fortotal thyroidectomy in newly diagnosed patients, and its incidence in differentiated thyroid cancer is 5%-34%, belonging to T3-T4 stage.In the eighth edition of thyroid cancer AJCC staging, the T3 stage was first divided into T3a (tumor>4 cm and limited to the thyroid) and T3b (gross extrathyroidal extension invading only strap muscles from a tumor of any size), and the "minimal extrathyroidal extension(tumor invasion intoperithyroidal soft tissue or strap muscle invasion)"of the seventh edition was removed from the T stage and changed to the gross extrathyroidal extension invading only strap muscles, but there is still much controversy. It can be seen that different degrees of "extrathyroidal extension" have significant differences in the survival and prognosis of thyroid cancer. This article reviews the latest research progress of extrathyroidal extension, and discusses the significance and clinical research progress of it.