Thyroid Cancer Staging 

Updated: Nov 17, 2015
  • Author: Eric J Lentsch, MD; Chief Editor: Jules E Harris, MD, FACP, FRCPC  more...
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TNM Classification for Thyroid Cancer

The TNM classification for thyroid cancer is provided below. [1, 2]

Table. TNM Classification for Thyroid Cancer (Open Table in a new window)

Primary tumor (T)
TX Primary tumor cannot be assessed
T0 No evidence of primary tumor is found
T1 Tumor size ≤ 2 cm in greatest dimension and is limited to the thyroid
T1a Tumor ≤ 1 cm, limited to the thyroid
T1b Tumor > 1 cm but ≤ 2 cm in greatest dimension, limited to the thyroid
T2 Tumor size > 2 cm but ≤ 4 cm, limited to the thyroid.
T3 Tumor size >4 cm, limited to the thyroid or any tumor with minimal extrathyroidal extension (eg, 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 vessel
All anaplastic carcinomas are considered stage IV:
T4a Intrathyroidal anaplastic carcinoma
T4b Anaplastic carcinoma with gross extrathyroid extension
Regional lymph nodes (N)
Regional lymph nodes are the central compartment, lateral cervical, and upper mediastinal lymph nodes:
NX Regional nodes cannot be assessed
N0 No regional lymph node metastasis
N1 Regional lymph node metastasis
N1a Metastases to level VI (pretracheal, paratracheal, and prelaryngeal/Delphian lymph nodes)
N1b Metastases 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 is found
M1 Distant metastasis is present

Table. Stage grouping (Open Table in a new window)

Stage grouping
Separate stage groupings are recommended for papillary or follicular (differentiated), medullary, and anaplastic (undifferentiated) carcinoma
Papillary and follicular thyroid cancer (age < 45y):
Stage T N M
I Any T Any N M0
II Any T Any N M1
Papillary and follicular; differentiated (age ≥ 45y):
Stage T N M
I T1 N0 M0
II T2 N0 M0
III T3 N0 M0
IVA T1-3 N1a M0
T4a N1b M0
IVB T4b Any N M0
IVC Any T Any N M1
Anaplastic carcinoma (all anaplastic carcinomas are considered stage IV):
Stage T N M
IVA T4a Any N M0
IVB T4b Any N M0
IVC Any T Any N M1
Medullary carcinoma (all age groups):
Stage T N M
I T1 N0 M0
II T2, T3 N0 M0
III T1-T3 N1a M0
IVA T4a N0 M0
T4a N1a M0
T1 N1b M0
T2 N1b M0
T3 N1b M0
T4a N1b M0
T4a N0, N1b M0
T1-T4a N1b M0
IVB T4b Any N M0
IVC Any T Any N M1