TG and neoplasm: Patients with macroscopic invasion of tumor into the perithyroidal soft tissues (gross extrathyroidal extension), incomplete tumor resection, distant metastases, postoperative serum thyroglobulin (Tg) suggestive of distant metastases, pathologic N1 with any metastatic lymph node 3 cm in largest dimension, or follicular thyroid cancer with extensive vascular invasion (> 4 foci of vascular invasion) were defined as high risk group in thyroid cancer [8].