Table 1.

ATA 2009 Risk Stratification System with Proposed Modifications.2

Risk Level Clinico-pathological Features
ATA Low Risk Papillary Thyroid Cancer (with all of the following):
  • No local or distant metastases
  • All macroscopic tumor has been resected
  • No tumor invasion of loco-regional tissues or structures
  • The tumor does not have aggressive histology (e.g. tall cell, hobnail variant, columnar cell carcinoma)
  • If 131I is given, there are no RAI avid metastatic foci outside the thyroid bed on the first post-treatment whole-body RAI scan
  • No vascular invasion

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 V600E BRAF mutated (if known)*
ATA Intermediate Risk Microscopic invasion of tumor into the perithyroidal soft tissues
RAI avid metastatic foci in the neck on the first post-treatment whole-body RAI scan
Aggressive histology (e.g. tall cell, hobnail variant, columnar cell carcinoma)
Papillary thyroid cancer with vascular invasion
Clinical N1 or >5 pathologic N1 with all involved lymph nodes <3 cm in largest dimension*
Multifocal papillary microcarcinoma with extrathyroidal extension and V600E BRAF mutated (if known)*
ATA High Risk Macroscopic invasion of tumor into the perithyroidal soft tissues (gross extrathyroidal extension)
Incomplete tumor resection
Distant metastases
Postoperative serum thyroglobulin suggestive of distant metastases
Pathologic N1 with any metastatic lymph node ≥3 in largest dimension*
Follicular thyroid cancer with extensive vascular invasion (>4 foci of vascular invasion)*

Table from the ATA thyroid cancer guidelines.2 Used with permission from the American Thyroid Association.

* Proposed modifications, not present in the original 2009 initial risk stratification system.
RMMJ Rambam Maimonides Medical Journal Rambam Health Care Campus 2016 January; 7(1): e0004. ISSN: 2076-9172
Published online 2016 January 28. doi: 10.5041/RMMJ.10231.