Medullary thyroid cancer (staging)

Last revised by Francis Deng on 9 Apr 2019

Medullary thyroid cancer staging refers to TNM staging of medullary thyroid carcinomasPapillary, follicular, and anaplastic thyroid carcinomas have similar TNM category definitions but different prognostic stage group definitions. 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: advanced disease with 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 I
    • T1, N0, M0
  • stage II
    • [T2, T3], N0, M0
  • stage III
    • [T1, T2, T3], N1a, M0
  • stage IVA
    • [T1, T2, T3], N1b, M0
    • T4a, [Any N], M0
  • stage IVB
    • T4b, [Any N], M0
  • stage IVC
    • [Any T], [Any N], M1

Since the 7th edition, upper mediastinal lymph nodes were added to the N1a category.

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