Table 2.

American Joint Committee on Cancer (AJCC] TNM Staging for Thyroid Cancer⁺

Primary Tumor (T)
TX	Primary tumor cannot be assessed
T0	No evidence of primary tumor
T1	Tumor ≤ 2 cm, limited to the thyroid
T1a	Tumor ≤ 1 cm, limited to the thyroid
T1b	Tumor >1 cm but < 2 cm, limited to the thyroid
T2	Tumor >2 cm but < 4 cm, limited to the thyroid
T3	Tumor > 4 cm, limited to the thyroid or minimal extrathyroid extension (sternothyroid or perithyroid soft tissues)
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 incases carotid artery or mediastinal vessels
Regional Lymph Nodes (N)
NX	Regional lymph nodes cannot be assessed
N0	No regional lymph node metastasis
N1	Regional lymph nodes metastasis
N1a	Metastasis to Level VI lymph nodes
N1b	Metastasis to unilateral, bilateral, or contralateral cervical [levels I, II, III, IV, or V) or superior mediastinal (level VII) lymph nodes
Distant Metastasis (M)
M0	No distant metastasis
M1	Distant metastasis
STAGE GROUPING:
Differentiated Cancers& < 45 years old
Stage I	Any T Any N M0
Stage II	Any T Any N M1
Differentiated Cancer ≥ 45 years old
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
Medullary Carcinoma
Stage I	T1 N0 M0
Stage II	T2 N0 M0
	T3 N0 M0
Stage III	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
Anaplastic Carcinomas $
Stage IVA	T4a Any N M0
Stage IVB	T4b Any N M0
Stage IVC	Any T Any N M1

⁺AJCC TNM Staging Manual, 7^th ed., 2010

^*All anaplastic tumors are considered T4 tumors

^&Papillary and follicular carcinomas are considered differentiated thyroid cancers

^$A11 anaplastic carcinomas are considered Stage IV