Table 1.

TNM classification for thyroid cancer

T (TUMOR)	N (LYMPH NODE METASTASES)	M (DISTANT METASTASES)
T1 £ 2 cm (T1a £ 1cm T1b 1-2 cm)	N0 absent	M0 absent
T2 2-4 cm	N1a metastases at VI level	M1 distant metastases
T3 > 4cm confined to the thyroid or with minimum extrathyroid invasion	N1b neck metastases (lateral) or in the upper mediastinum
T4a invading subcutaneous tissue, larynx, trachea, esophagus, or laryngeal recurrent
T4b invading pre-vertebral fascia or involving the carotid or mediastinal vessels
Tx unknown size without extrathyroid invasion	Nx lymph nodes not assessed	Mx not assessed

TNM: Classification proposed by the American Joint Committee on Cancer (2002).