TG and neoplasm: The high-risk group is characterized by any of the following features: macroscopic tumor invasion into the peri-thyroid soft tissues (i.e., extensive ETE); incomplete tumor resection; pathologic N1 disease with any lymph node measuring ≥3 cm in the greatest dimension; distant metastases; elevated postoperative serum thyroglobulin suggestive of distant metastases; or follicular thyroid carcinoma with extensive vascular invasion, defined as more than 4 foci of vascular involvement [21].