Thyroid cancer staging
Thyroid cancer staging is done with the TNM staging system.
TNM staging system
Tumour stage not including anaplastic carcinoma
| T stage | Size/criteria | Other requirements | Comment |
|---|---|---|---|
| pT1a | 1 cm or less | limited to thyroid | very common |
| pT1b | >1 cm and <=2 cm | limited to thyroid | |
| pT2 | >2 cm and <=4 cm | limited to thyroid | |
| pT3a | >4 cm | limited to thyroid | changed from AJCC 7th Ed. |
| pT3b | extension into strap muscles | strap muscles include: sternothyroid m., sternothyroid, thyrohyoid, omohyoid | changed from AJCC 7th Ed. |
| pT4a | any size | any of the following: subcutaneous tissue, trachea, esophagus, larynx, recurrent laryngeal nerve | |
| pT4b | any size | any of the following: mediastinal vessels, encasing carotid artery, prevertebral fascia |
Lymph nodes
| N stage | Criteria | Comment |
|---|---|---|
| pN0 | negative for lymph node metastasis | |
| pN1a | metastasis to level VI or VII | level VI = pretracheal, paratracheal, prelaryngeal/Delphian, perithyroidal; VII = mediastinal lymph nodes |
| pN1b | metastasis to level I, II, III, IV, V, or retropharyngeal | (level VII changed to pN1a in AJCC 8th Ed.) |
Note:
- Central neck dissection = level VI and VII[1]