T1—2 cm or less, limited to thyroid T1a—1 cm or less, limited to thyroid T1b—1 to 2 cm, limited to thyroid | N1—regional lymph metastasis N1a—metastasis to level VI lymph nodes N1b—metastasis to ipsilateral, bilateral, or contralateral level I, II, III, IV, or V lymph nodes or level VII lymph nodes |
T4a—moderately advanced disease; any size tumor extending beyond thyroid capsule to subcutaneous soft tissue, trachea, esophagus, larynx, or recurrent laryngeal nerve T4b—very advanced disease; invades prevertebral fascia or encases carotid artery or mediastinal vessel All anaplastic cancers are T4: T4a—intrathyroidal anaplastic carcinoma T4b—gross extrathyroid extension | M1—distant metastasis |