ATA Low Risk | Papillary thyroid cancer (with all of the following): • Does not have local or distant metastases • The entire macroscopic tumor has been resected • It has no tumor invasion of loco-regional structures or tissues • The tumor has no aggressive histology (high cell carcinoma, Hobnail variant, and columnar cell carcinoma) • If I131 is administered, avid metastatic foci outside the thyroid bed should not be identified in the first post-treatment full-body thyroid scan • Without vascular invasion • cN0 or ≤5 pN1 micro-metastases (<0.2 cm in the largest dimension) Papillary thyroid cancer of intra-thyroid follicular variant, encapsulated Intra-thyroid well differentiated follicular thyroid cancer with capsular invasion and no or minimal vascular invasion (<4 foci) Intra-thyroid, unifocal or multifocal papillary microcarcinoma, including mutated BRAF V600E (if known) |
ATA Intermediate Risk | Microscopic invasion of the tumor to the peri-thyroid soft tissues Avid metastatic foci of radioactive iodine in the neck at the first full-body scan post-treatment Aggressive histology (high cell carcinoma, Hobnail variant, and columnar cell carcinoma) Papillary thyroid cancer with vascular invasion cN1 or >5 pN1 with all lymph nodes affected <3 cm in greatest dimension Multifocal papillary microcarcinoma with extra thyroid extension and mutated BRAF V600E (if known) |
ATA High Risk | Macroscopic invasion of peri-thyroid soft tissue tumor Incomplete tumor resection Distant metastasis Postoperative serum thyroglobulin suggestive of distant metastases pN1 with any metastatic lymph node ≥ 3 cm in greatest dimension Follicular thyroid cancer with extensive vascular invasion (>4 foci of vascular invasion) |