The 8th edition of the American Joint Commission on Cancer (AJCC) made several modifications to the staging of thyroid cancers.
Thyroid tumors: papillary, follicular, Hurthle cell, poorly differentiated, anaplastic
General rules for multiple tumors:
(1) Multifocal tumors are designated "(m)".
(2) TNM coding is based on the largest tumor (presumably if of the same histologic type).
Parameters:
(1) diameter in centimeters
(2) gross extrathyroid spread
(3) metastases to regional lymph nodes
(4) distant metastases
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Diameter in cm
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Extrathyroid Extension
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T Code
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<= 1 cm
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no
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T1a
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1.01 to 2 cm
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no
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T1b
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2.01 to 4 cm
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no
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T2
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> 4 cm
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no
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T3a
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NA
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yes, into strap muscles
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T3b
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NA
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yes, major neck structures
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T4
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Modifications:
(1) TX: cannot be assessed
(2) T0: no evidence of primary tumor
(3) T4a: subcutaneous soft tissue, larynx, trachea, esophagus, recurrent laryngeal nerve
(4) T4b: prevertebral fascia, carotid artery, mediastinal blood vessels
where:
• Strap muscles inlcude the sernohyoid, sternothyroid, thyrohyoid and omohyoid muscles.
• Microscopic extension beyond the thyroid is not included in decision-making.
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Nodal Metastases
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N Code
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cannot be assessed
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NX
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none
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N0
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any
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N1
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Modifications:
(1) N0a: by cytology or histology
(2) N0b: by imaging studies or clinical exam
(3) N1a: unilateral or bilateral involvement of VI or VII lymph nodes (pretracheal, paratracheal, prelaryngeal, upper mediastinal)
(4) N1b: unilateral or bilateral involvement of I, II, III, IV or V level lymph nodes; retropharyngeal lymph nodes
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Distant Metastases
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M Code
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no
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M0
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yes
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M1
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