Table 1 TNM staging for differentiated cancers (papillary and follicular)
Primary Tumor (T) | |
|---|---|
 TX | Primary tumor cannot be assessed |
 T0 | No evidence of primary tumor |
 T1 | Tumor 2 cm or less in greatest dimension limited to the thyroid |
 T1a | Tumor 1 cm or less, limited to the thyroid |
 T1b | Tumor more than 1 cm but not more than 2 cm in greatest dimension, limited to the thyroid |
 T2 | Tumor more than 2 cm but not more than 4 cm in greatest dimension limited to the thyroid |
 T3 | Tumor more than 4 cm in greatest dimension limited to the thyroid or any tumor with minimal extrathyroid extension (e.g., extension to sternothyroid muscle or perithyroid soft tissues) |
 T4a | Moderately advanced disease: Tumor of any size extending beyond the thyroid capsule to invade subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve |
 T4b | Very advanced disease Tumor invades prevertebral fascia or encases carotid artery or mediastinal vessels |
Regional Lymph Nodes (N) | Regional lymph nodes are the central compartment, lateral cervical, and upper mediastinal lymph nodes. |
 NX | Regional lymph nodes cannot be assessed |
 N0 | No regional lymph node metastasis |
 N1 | Regional lymph node metastasis |
 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) | |
 M0 | No distant metastasis |
 M1 | Distant metastasis |
Age less than 45Â years | |
 Stage I | Any T Any N M0 |
 Stage II | Any T Any N M1 |
Age greater than 45Â years | |
 Stage I | T1 N0 M0 |
 Stage II | T2 N0 M0 |
 Stage III | T3 N0 M0 T1 N1a M0 T2 N1a M0 T3 N1a M0 |
 Stage IVA | T4a N0 M0 T4a N1a M0 T1 N1b M0 T2 N1b M0 T3 N1b M0 T4a N1b M0 |
 Stage IVB | T4b Any N M0 |
 Stage IVC | Any T Any N M1 |