Anaplastic Thyroid Carcinoma
Staging (AJCC 8th Edition)
All ATC is considered stage IV.
| T | N | M | |
| IVA | T1-T3a | N0/NX | M0 |
| IVB | T1-T3a | N1 | M0 |
| T3b | Any N | M0 | |
| T4 | Any N | M0 | |
| IVC | Any T | Any N | M1 |
Advanced T stages are defined by extrathyroidal invasion.
| T1a = ≤1cm | T3b = invading strap muscles only |
| T1b = >1cm - ≤2cm | T4a = invading beyond strap muscle |
| T2 = >2cm - ≤4cm | T4b = invading into prevertebral fascia, encasing carotid or mediastinal vessels |
| T3a = >4cm |