Anaplastic thyroid cancer (staging)

Anaplastic thyroid cancer staging refers to TNM staging of anaplastic thyroid carcinomas. Papillaryfollicular, and medullary thyroid carcinomas are staged separately. The following article reflects the 8th edition manual published by the American Joint Committee on Cancer, which is used for staging starting January 1, 2018 1,2.

  • TX: primary tumor cannot be assessed 
  • T0: no evidence of primary tumor
  • T1: tumor ≤2 cm in greatest dimension 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 gross extrathyroidal extension invading only strap muscles
  • T4: gross extrathyroidal extension beyond the strap muscles
  • NX: regional lymph nodes cannot be assessed
  • N0: no regional lymph node metastasis
    • N0a: one or more lymph nodes confirmed benign by cytology/histology
    • N0b: no radiologic or clinical evidence of regional lymph node metastasis
  • N1: regional lymph node metastasis
    • N1a: central lymph node metastases to level VI (pretracheal, paratracheal, and prelaryngeal/Delphian lymph nodes) or level VII (upper mediastinal); can be unilateral or bilateral
    • N1b: lateral neck lymph node metastases (levels I, II, III, IV, or V, or retropharyngeal); can be unilateral, bilateral, or contralateral

The terms pM0 and MX are not valid TNM categories. The following categories may be used:

  • cM0: no evidence of metastases
  • cM1: distant metastasis
  • pM1: distant metastasis, microscopically confirmed
  • stage IVA
    • [T1, T2, T3a], [N0, NX], M0
  • stage IVB
    • [T1, T2, T3a], N1, M0
    • [T3b, T4], [Any N], M0
  • stage IVC
    • [Any T], [Any N], M1

Compared to the 7th edition, anaplastic tumors are no longer automatically classified as T4 disease and T category is defined the same as for differentiated thyroid cancers. The stage groups were modified accordingly to reflect the poor prognosis of anaplastic thyroid cancer: stage IVA indicates intrathyroidal disease, stage IVB indicates extrathyroidal extension or regional nodal metastases, and stage IVC indicates distant metastases.

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Article information

rID: 67498
Section: Staging
Synonyms or Alternate Spellings:
  • Anaplastic thyroid carcinoma (staging)

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