TNM Classification for Thyroid Cancer
The American Joint Committee on Cancer (AJCC) used different tumor-node-metastasis (TNM) classification for differentiated and anaplastic thyroid cancer and for medullary thyroid cancer, as outlined below. [1, 2, 3]
Table 1. TNM Classification for Differentiated and Anaplastic 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 gross extrathyroidal extension invading only strap muscles |
| T3a | Tumor size > 4 cm, limited to the thyroid |
| T3b | Any size tumor with gross extrathyroidal extension invading only strap muscles (eg, extension to sternothyroid muscle or perithyroid soft tissues) |
T4a |
Any size tumor with gross extrathyroidal extension invading subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve |
T4b |
Any size tumor with gross extrathyroidal extension invading prevertebral fascia or encasing the carotid artery or mediastinal vessels |
All categories may be subdivided: (s) solitary tumor and (m) multifocal tumor (the largest determines classification) |
|
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 |
| N0a | One or more cytologically or histologically confirmed benign lymph nodes |
| N0b | No radiologic or clinical evidence of locoregional lymph node metastasis |
N1 |
Regional lymph node metastasis |
N1a |
Metastases to level VI or VI (pretracheal, paratracheal, or prelaryngeal/Delphian or upper mediastinal) lymph nodes |
N1b |
Metastases to unilateral, bilateral, or contralateral neck lymph nodes (levels I, II, III, IV, or V) or retropharyngeal lymph nodes |
Distant metastasis (M) |
|
M0 |
No distant metastasis is found |
M1 |
Distant metastasis is present |
Table 2. TNM Classification for Medullary 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 gross extrathyroidal extension invading only strap muscles |
| T3a | Tumor size > 4 cm, limited to the thyroid |
| T3b | Any size tumor with gross extrathyroidal extension invading only strap muscles (eg, extension to sternothyroid muscle or perithyroid soft tissues) |
T4a |
Moderately advanced disease; Any size tumor with gross extrathyroidal extension invading subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve |
T4b |
Very advanced disease; Any size tumor with extension toward the spine or into nearby large blood vessels, gross extrathyroidal extension invading prevertebral fascia or encasing the carotid artery or mediastinal vessels |
|
|
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 |
| N0a | One or more cytologically or histologically confirmed benign lymph nodes |
| N0b | No radiologic or clinical evidence of locoregional lymph node metastasis |
N1 |
Regional lymph node metastasis |
N1a |
Metastases to level VI or VI (pretracheal, paratracheal, or prelaryngeal/Delphian or upper mediastinal) lymph nodes; can be unilateral or bilateral disease |
N1b |
Metastases to unilateral, bilateral, or contralateral neck lymph nodes (levels I, II, III, IV, or V) or retropharyngeal lymph nodes |
Distant metastasis (M) |
|
M0 |
No distant metastasis is found |
M1 |
Distant metastasis is present |
Table3. Stage grouping (Open Table in a new window)
Stage grouping |
|||
Differentiated, medullary, and anaplastic carcinoma have separte stage groupings |
|||
Differentiated (age < 55y): |
|||
Stage |
T |
N |
M |
I |
Any T |
Any N |
M0 |
II |
Any T |
Any N |
M1 |
Differentiated (age ≥ 55y): |
|||
Stage |
T |
N |
M |
I |
T1 |
N0/NX |
M0 |
| T2 | N0/NX | M0 | |
II |
T1 |
N1 | M0 |
| T2 | N1 | M0 | |
| T3a/T3b | Any N | M0 | |
III |
T4a | Any N |
M0 |
IVA |
T4b | Any N |
M0 |
IVB |
Any T |
Any N |
M1 |
Anaplastic carcinoma (all anaplastic carcinomas are considered stage IV): |
|||
Stage |
T |
N |
M |
IVA |
T1-T3a |
N0/NX |
M0 |
IVB |
T1-T3a |
Any N |
M0 |
| T3b | Any N | M0 | |
| T4 | Any N | M0 | |
IVC |
Any T |
Any N |
M1 |
Medullary carcinoma: |
|||
Stage |
T |
N |
M |
I |
T1 |
N0 |
M0 |
II |
T2, T3 |
N0 |
M0 |
III |
T1-T3 |
N1a |
M0 |
IVA |
T4a |
Any N |
M0 |
T1-T3 |
N1b |
M0 |
|
IVB |
T4 |
N0 |
M0 |
IVC |
Any T |
Any N |
M1 |
Tables
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 gross extrathyroidal extension invading only strap muscles |
| T3a | Tumor size > 4 cm, limited to the thyroid |
| T3b | Any size tumor with gross extrathyroidal extension invading only strap muscles (eg, extension to sternothyroid muscle or perithyroid soft tissues) |
T4a |
Any size tumor with gross extrathyroidal extension invading subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve |
T4b |
Any size tumor with gross extrathyroidal extension invading prevertebral fascia or encasing the carotid artery or mediastinal vessels |
All categories may be subdivided: (s) solitary tumor and (m) multifocal tumor (the largest determines classification) |
|
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 |
| N0a | One or more cytologically or histologically confirmed benign lymph nodes |
| N0b | No radiologic or clinical evidence of locoregional lymph node metastasis |
N1 |
Regional lymph node metastasis |
N1a |
Metastases to level VI or VI (pretracheal, paratracheal, or prelaryngeal/Delphian or upper mediastinal) lymph nodes |
N1b |
Metastases to unilateral, bilateral, or contralateral neck lymph nodes (levels I, II, III, IV, or V) or retropharyngeal lymph nodes |
Distant metastasis (M) |
|
M0 |
No distant metastasis is found |
M1 |
Distant metastasis is present |
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 gross extrathyroidal extension invading only strap muscles |
| T3a | Tumor size > 4 cm, limited to the thyroid |
| T3b | Any size tumor with gross extrathyroidal extension invading only strap muscles (eg, extension to sternothyroid muscle or perithyroid soft tissues) |
T4a |
Moderately advanced disease; Any size tumor with gross extrathyroidal extension invading subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve |
T4b |
Very advanced disease; Any size tumor with extension toward the spine or into nearby large blood vessels, gross extrathyroidal extension invading prevertebral fascia or encasing the carotid artery or mediastinal vessels |
|
|
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 |
| N0a | One or more cytologically or histologically confirmed benign lymph nodes |
| N0b | No radiologic or clinical evidence of locoregional lymph node metastasis |
N1 |
Regional lymph node metastasis |
N1a |
Metastases to level VI or VI (pretracheal, paratracheal, or prelaryngeal/Delphian or upper mediastinal) lymph nodes; can be unilateral or bilateral disease |
N1b |
Metastases to unilateral, bilateral, or contralateral neck lymph nodes (levels I, II, III, IV, or V) or retropharyngeal lymph nodes |
Distant metastasis (M) |
|
M0 |
No distant metastasis is found |
M1 |
Distant metastasis is present |
Stage grouping |
|||
Differentiated, medullary, and anaplastic carcinoma have separte stage groupings |
|||
Differentiated (age < 55y): |
|||
Stage |
T |
N |
M |
I |
Any T |
Any N |
M0 |
II |
Any T |
Any N |
M1 |
Differentiated (age ≥ 55y): |
|||
Stage |
T |
N |
M |
I |
T1 |
N0/NX |
M0 |
| T2 | N0/NX | M0 | |
II |
T1 |
N1 | M0 |
| T2 | N1 | M0 | |
| T3a/T3b | Any N | M0 | |
III |
T4a | Any N |
M0 |
IVA |
T4b | Any N |
M0 |
IVB |
Any T |
Any N |
M1 |
Anaplastic carcinoma (all anaplastic carcinomas are considered stage IV): |
|||
Stage |
T |
N |
M |
IVA |
T1-T3a |
N0/NX |
M0 |
IVB |
T1-T3a |
Any N |
M0 |
| T3b | Any N | M0 | |
| T4 | Any N | M0 | |
IVC |
Any T |
Any N |
M1 |
Medullary carcinoma: |
|||
Stage |
T |
N |
M |
I |
T1 |
N0 |
M0 |
II |
T2, T3 |
N0 |
M0 |
III |
T1-T3 |
N1a |
M0 |
IVA |
T4a |
Any N |
M0 |
T1-T3 |
N1b |
M0 |
|
IVB |
T4 |
N0 |
M0 |
IVC |
Any T |
Any N |
M1 |
