Table 1.
UICC TNM classification.
| T—Primary Tumor | T/N/M | Characterization |
|---|---|---|
| T1 | Tumor 2 cm or less in greatest dimension, limited to the thyroid | |
| T1a | Tumor ≤ 1 cm in greatest dimension, limited to the thyroid | |
| T1b | Tumor > 1 cm but ≤2 cm in greatest dimension, limited to the thyroid | |
| T2 | Tumor > 2 cm but ≤4 cm in greatest dimension, limited to the thyroid | |
| T3 | Tumor > 4 cm in greatest dimension, limited to the thyroid or with gross extrathyroidal extension invading only strap muscles (sternohyoid, sternothyroid or omohyoid muscles) | |
| T4a | Tumor extends beyond the thyroid capsule and invades any of the following: subcutaneous soft tissues, larynx, trachea, esophagus, recurrent laryngeal nerve | |
| T4b | Tumor invades prevertebral fascia or encasing the carotid artery or mediastinal vessels from a tumor of any size | |
| N—regional lymph nodes | ||
| N0 | No evidence of locoregional lymph node metastasis | |
| N1a | Metastasis to level VI (pretracheal, paratracheal and prelaryngeal/Delphian lymph nodes) or upper/superior mediastinum | |
| N1b | Metastasis in other unilateral, bilateral or contralateral cervical compartments (levels I, II, III, IV or V) or retropharyngeal | |
| M—distant metastasis | ||
| M0 | No distant metastasis | |
| M1 | Distant metastasis |