Radiation Oncology/Thyroid/Staging

Thyroid Cancer Staging

AJCC Staging

AJCC 7th Edition (2009)
Primary tumor

• T0 - No evidence of primary tumor
• T1 - Tumor 2 cm or less, limited to the thyroid
  • T1a - Tumor 1 cm or less
  • T1b - Tumor >1 cm but <= 2 cm
• T2 - Tumor >2 cm but <=4 cm, limited to the thyroid
• T3 - Tumor >4 cm, limited to the thyroid, or any tumor with minimal extrathyroidal extension (e.g. extension to sternothyroid muscle or perithyroid soft tissues)
• T4a - Tumor extending beyond the thyroid capsule to invade subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal N
• T4b - Tumor invades prevertebral fascia or encases carotid artery or mediastinal vessels

Anaplastic carcinoma: All anaplastic carcinomas are considered T4 tumors

• T4a - Intrathyroidal anaplastic carcinoma
• T4b - Anaplastic carcinoma with gross extrathyroid extension

Nodes

• N0 - no regional lymph node metastasis
• N1 - regional lymph node metastasis
  • N1a - Metastasis to Level VI (pretracheal, paratracheal, and prelaryngeal/Delphian lymph nodes)
  • N1b - Metastasis to unilateral, bilateral, or contralateral cervical (Levels I-V) or retropharyngeal or superior mediastinal lymph nodes (Level VII)

Distant Metastasis

• M0 - none
• M1 - yes

Stage grouping

Papillary or follicular

(Age under 45 years)

• Stage I - Any T, Any N, M0
• Stage II - Any T, Any N, M1
  
  

Papillary or follicular

(45 years and older)

• Stage I - T1 N0 M0
• Stage II - T2 N0 M0
• Stage III - T3 or N1a
• Stage IVA - T4a or N1b
• Stage IVB - T4b, Any N, M0
• Stage IVC - M1

Medullary carcinoma (all age groups)

• Stage I - T1 N0 M0
• Stage II - T2-T3 N0 M0
• Stage III - T1-3 N1a M0
• Stage IVA - T4a or N1b
• Stage IVB - T4b, Any N, M0
• Stage IVC - M1

Anaplastic carcinoma

All anaplastic carcinomas are considered Stage IV

• Stage IVA - T4a, Any N, M0
• Stage IVB - T4b, Any N, M0
• Stage IVC - M1

Changes from 6th edition

Subdivided T1 into T1a and T1b

Other Staging Systems

See also: Thyroid cancer prognostic indices (e.g. AMES, AGES, MACIS)

National Thyroid Cancer Treatment Cooperative Study (NTCTCS) Staging Classification

NTCTCS Staging
adapted from PMID 9731906 (Sherman SI, Cancer 1998)

	Papillary Carcinoma		Follicular Carcinoma
	Age < 45	Age ≥ 45	Age < 45	Age ≥ 45
Primary tumor size (cm)
<1	I	I	I	II
1-4	I	II	I	III
>4	II	III	II	III
Primary tumor characteristics
Microscopic multifocal	I	II	I	III
Macroscopic multifocal or Macroscopic tumor capsule invasion	I	II	II	III
Microscopic extraglandular invasion	I	II	I	III
Macroscopic extraglandular invasion	II	III	II	III
Poorly differentiated	NA	NA	III	III
Metastases
Cervical lymph node metastases	I	III	I	III
Extracervical (distant) metastases	III	IV	III	IV