| Low risk | | Papillary thyroid cancer with all of the following present: | - No local or distant metastases
| - All macroscopic tumor has been resected
| - No invasion of locoregional tissues
| - Tumor does not have aggressive histology (aggressive histologies include tall cell, insular, columnar cell carcinoma, Hürthle cell carcinoma, follicular thyroid cancer, hobnail variant)
| | | - No 131I uptake outside the thyroid bed on the post-treatment scan, if done
| - Clinical N0 or ≤5 pathologic N1 micrometastases (<0.2 cm in largest dimension)*
| | Intrathyroidal, encapsulated follicular variant of papillary thyroid cancer* | | Intrathyroidal, well-differentiated follicular thyroid cancer with capsular invasion and no or minimal (<4 foci) vascular invasion* | | Intrathyroidal, papillary microcarcinoma, unifocal or multifocal, including BRAF V600E mutated (if known)* | | | Intermediate risk | | Any of the following present: | | Microscopic invasion into the perithyroidal soft tissues | | Cervical lymph node metastases or 131I avid metastatic foci in the neck on the post-treatment scan done after thyroid remnant ablation | | Tumor with aggressive histology or vascular invasion (aggressive histologies include tall cell, insular, columnar cell carcinoma, Hürthle cell carcinoma, follicular thyroid cancer, hobnail variant) | | Clinical N1 or >5 pathologic N1 with all involved lymph nodes <3 cm in largest dimension* | | Multifocal papillary thyroid microcarcinoma with extrathyroidal extension and BRAF V600E mutated (if known)* | | | High risk | | Any of the following present: | | Macroscopic tumor invasion | | Incomplete tumor resection with gross residual disease | | Distant metastases | | Postoperative serum thyroglobulin suggestive of distant metastases | | Pathologic N1 with any metastatic lymph node ≥3 cm in largest dimension* | | Follicular thyroid cancer with extensive vascular invasion (>4 foci of vascular invasion)* | |
