ATA high risk (>20%) category includes patients with: (i) macroscopic invasion of tumor into the perithyroidal soft tissues; (ii) incomplete tumor resection; (iii) distant metastases; (iv) post-operative serum Tg suggestive of distant metastases; (v) pathologic N1 with any metastatic lymph node ≥3 cm in largest dimension; and (vi) follicular thyroid cancer with extensive vascular invasion (>4 foci of vascular invasion). Here, TG is linked to neoplasm.