Intermediate-risk patients are those with any of the following criteria: microscopic tumour invasion into the perithyroidal tissues at initial surgery, cervical lymph node metastases or 131I uptake outside the thyroid bed on the initial post-treatment scan, or tumour with aggressive histology or vascular invasion. Finally, high-risk patients have macroscopic tumour invasion, incomplete tumour resection, distant metastases or elevated thyroglobulin out of proportion to what is seen on the post-treatment scan (Cooper et al., 2009). This stratification was designed to help identify patients who are at higher risk for recurrent disease and may benefit from more aggressive postoperative management (Cooper et.
