Table 5.
American Joint Committee on Cancer TNM Classification System for Differentiated Thyroid Carcinomaa
| Primary tumor (T) | ||
| TX | Size not assessed, limited to the thyroid | |
| T1 | T1a | ≤ 1 cm, limited to the thyroid |
| T1b | > 1 cm but ≤ 2 cm, limited to the thyroid | |
| T2 | > 2 cm but ≤ 4 cm, limited to the thyroid | |
| T3 | > 4 cm, limited to the thyroid, or any tumor with minimal extrathyroid extension | |
| T4 | T4a | Tumor extends beyond the thyroid capsule to invade subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve |
| T4b | Tumor invades prevertebral fascia or encases carotid artery or mediastinal vessels | |
| Lymph nodes (N) | ||
| NX | Regional lymph nodes not assessed | |
| N0 | No regional lymph node metastasis | |
| N1 | N1a | Metastasis to level VI (pretracheal, paratracheal, and prelaryngeal/ Delphian lymph nodes) |
| N1b | Metastasis to unilateral, bilateral, or contralateral cervical levels I, II, III, IV, or V) or retropharyngeal or superior mediastinal lymph nodes (level VII) | |
| Distant metastasis (M) | ||
| MX | Distant metastasis not assessed | |
| M0 | No distant metastasis | |
| M1 | Distant metastasis | |
a
Pediatric patients are considered to have stage II disease if distant metastases are identified (M1); otherwise, all pediatric patients are considered to have stage I disease.
Used with the permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, 7th edition (2010) published by Springer Science and Business Media LLC, www.springer.com (69).