TNM Definitions
AJCC Stage Groupings

The staging systems for oropharyngeal cancer are all clinical, based on the best possible estimate of the extent of disease before treatment. The assessment of the primary tumor is based on inspection and palpation when possible and by indirect mirror examination. The appropriate nodal drainage areas are examined by careful palpation.

The tumor must be confirmed histologically, and any other pathologic data obtained from a biopsy may be included. Additional radiographic studies may be included. As an adjunct to clinical examination, magnetic resonance imaging is used to evaluate the extent of disease in the soft tissues; computed tomography is used to evaluate the mandible and maxilla.[1] Positron emission tomography has been investigated as an imaging modality for recurrent oropharyngeal cancer.[2]

Complete endoscopy, typically under general anesthesia, is performed after completion of other staging studies to assess the surface extent of the tumor accurately, to assess deep involvement by palpation for muscle invasion, and to facilitate biopsy. Because of the incidence of multiple primary tumors occurring simultaneously, a careful search for other primary tumors of the upper aerodigestive tract is indicated.[3]

The American Joint Committee on Cancer (AJCC) has designated staging by TNM classification.[3] Nonepithelial tumors such as those of lymphoid tissue, soft tissue, bone, and cartilage are not included.

Primary tumor (T)

• TX: Primary tumor cannot be assessed
• T0: No evidence of primary tumor
• Tis: Carcinoma in situ
• T1: Tumor 2 cm or smaller in greatest dimension
• T2: Tumor larger than 2 cm but 4 cm or smaller in greatest dimension
• T3: Tumor larger than 4 cm in greatest dimension
• T4a: Tumor invades the larynx, deep/extrinsic muscle of tongue, medial pterygoid, hard palate, or mandible
• T4b: Tumor invades lateral pterygoid muscle, pterygoid plates, lateral nasopharynx, or skull base or encases carotid artery

Regional lymph nodes (N)

• NX: Regional lymph nodes cannot be assessed
• N0: No regional lymph node metastasis
• N1: Metastasis in a single ipsilateral lymph node, 3 cm or smaller in greatest dimension
• N2: Metastasis in a single ipsilateral lymph node, larger than 3 cm but 6 cm or smaller in greatest dimension, or in multiple ipsilateral lymph nodes, 6 cm or smaller in greatest dimension, or in bilateral or contralateral lymph nodes, 6 cm or smaller in greatest dimension
  • N2a: Metastasis in a single ipsilateral lymph node larger than 3 cm but 6 cm or smaller in greatest dimension
  • N2b: Metastasis in multiple ipsilateral lymph nodes, 6 cm or smaller in greatest dimension
  • N2c: Metastasis in bilateral or contralateral lymph nodes, 6 cm or smaller in greatest dimension
• N3: Metastasis in a lymph node larger than 6 cm in greatest dimension

In clinical evaluation, the actual size of the nodal mass should be measured, and allowance should be made for intervening soft tissues. Most masses larger than 3 cm in diameter are not single nodes but confluent nodes or tumors in soft tissues of the neck. There are three stages of clinically positive nodes: N1, N2, and N3. The use of subgroups a, b, and c is not required but is recommended. Midline nodes are considered homolateral nodes.

Distant metastasis (M)

• MX: Distant metastasis cannot be assessed
• M0: No distant metastasis
• M1: Distant metastasis

Stage 0

• Tis, N0, M0

Stage I

• T1, N0, M0

Stage II

• T2, N0, M0

Stage III

• T3, N0, M0
• T1, N1, M0
• T2, N1, M0
• T3, N1, M0

Stage IVA

• T4a, N0, M0
• T4a, N1, M0
• T1, N2, M0
• T2, N2, M0
• T3, N2, M0
• T4a, N2, M0

Stage IVB

• T4b, any N, M0
• Any T, N3, M0

Stage IVC

• Any T, any N, M1

References

1. Weber AL, Romo L, Hashmi S: Malignant tumors of the oral cavity and oropharynx: clinical, pathologic, and radiologic evaluation. Neuroimaging Clin N Am 13 (3): 443-64, 2003.  [PUBMED Abstract]
   
   
2. Wong RJ, Lin DT, Schöder H, et al.: Diagnostic and prognostic value of [(18)F]fluorodeoxyglucose positron emission tomography for recurrent head and neck squamous cell carcinoma. J Clin Oncol 20 (20): 4199-208, 2002.  [PUBMED Abstract]
   
   
3. Pharynx (including base of tongue, soft palate and uvula). In: American Joint Committee on Cancer.: AJCC Cancer Staging Manual. 6th ed. New York, NY: Springer, 2002, pp 31-46.