AJCC 7th Edition TNM Score for Papillary or Follicular Well-Differentiated Thyroid Cancer (21)
| Score | Characteristics |
| Primary tumor (T) | |
| T1 | Tumor ≤ 2 cm, limited to thyroid; T1a: tumor ≤ 1 cm (microcarcinoma);T1b: tumor > 1 cm but ≤ 2 cm |
| T2 | Tumor > 2 cm but ≤ 4 cm, limited to thyroid |
| T3 | Tumor > 4 cm, limited to thyroid, or any tumor with minimal extrathyroid extension; for example, extension to sternothyroid muscle or perithyroid soft tissues |
| T4 | Advanced disease: T4a: tumor of any size extending beyond 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 |
| Regional nodes (N) | |
| N0 | No regional lymph node metastasis |
| N1 | Regional lymph node metastasis; N1a: metastasis to central neck compartment (cervical level VI); N1b: metastasis to unilateral, bilateral, or contralateral lateral neck compartments (cervical levels I, II, III, IV, or V) or retropharyngeal or superior mediastinal lymph nodes (cervical level VII) |
| Distant metastases (M) | |
| M0 | No distant metastasis |
| M1 | Distant metastasis |