External beam radiation therapy (EBRT) is only used in a very small percentage of patients with thyroid cancer. In principle, radiotherapy should be used in conjunction with surgery, mainly for postoperative radiotherapy.
The specific implementation should depend on the surgical resection, pathological type, lesion extent, age and other factors: (i) for less malignant cancers such as well-differentiated PTC or FTC, intervention should be considered only when re-surgical resection is not possible. ②Postoperative radiation therapy can be considered when the tumor involves more important areas (such as tracheal wall, prevertebral tissue, larynx, arterial wall or venous aneurysm embolus) and cannot be removed surgically, and 131I therapy is ineffective or is expected to be ineffective. ③For young patients, the pathological type is generally well differentiated, and they can survive with tumor for a long time even with recurrent metastasis, and both 131I treatment and reoperation are effective treatments, and the application of external radiation needs to be cautious. ④For PDTC or ATC, if there is residual or extensive lymph node metastasis after surgery, extensive postoperative radiation therapy should be given promptly to minimize the local recurrence rate and improve the prognosis.