Thyroid cancer staging

Dr Henry Knipe and Dr Jeremy Jones et al.

Successful treatment of thyroid malignancies highly depends on accurate preoperative staging, which is best done by combined ultrasound and postcontrast CT scan of the neck. For staging of the thyroid cancers (including papillaryfollicular and medullary) the TNM staging system is widely used.

For anaplastic cancer, there is no generally accepted stating system and all patients with anaplastic thyroid cancer are considered to have stage IV disease.

T: Tumour
  • TX: primary tumour cannot be assessed 
  • T0: no evidence of primary tumour
  • T1: tumour ≤2 cm in greatest dimension limited to the thyroid
    • T1a: tumour ≤1 cm, limited to the thyroid
    • T1b: tumour >1 cm but ≤2 cm in greatest dimension, limited to the thyroid
  • T2: tumour >2 cm but ≤4 cm in greatest dimension, limited to the thyroid
  • T3: tumour >4 cm in greatest dimension limited to the thyroid or any tumour with minimal extrathyroid extension (e.g. extension to sternothyroid muscle or perithyroid soft tissues)
  • T4: advanced disease
    • T4a: moderately advanced disease - tumour of any size extending beyond the thyroid capsule to invade subcutaneous soft tissues, larynx, trachea, oesophagus, or recurrent laryngeal nerve
    • T4b: very advanced disease - tumour invades prevertebral fascia or encases carotid artery or mediastinal vessels
    • cT4a: intrathyroidal anaplastic carcinoma
    • cT4b: anaplastic carcinoma with gross extrathyroid extension
N: Nodes
  • NX: regional lymph 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)
M: Metastases
  • MX: distant metastases cannot be assessed
  • M0: no distant metastasis
  • M1: distant metastasis

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