TNM Definitions
AJCC Stage Groupings

The staging system is clinical and 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 both indirect mirror examination and direct endoscopy when necessary. The tumor must be confirmed histologically, and any other pathological data obtained on biopsy may be included. Head and neck magnetic resonance imaging or computed tomography should be done prior to therapy to supplement inspection and palpation.[1] Additional radiographic studies may be included. The appropriate nodal drainage areas in the neck are examined by careful palpation.

The American Joint Committee on Cancer (AJCC) has designated staging by TNM classification.[2]

Primary tumor (T)

• TX: Primary tumor cannot be assessed
• T0: No evidence of primary tumor
• Tis: Carcinoma in situ

Supraglottis

• T1: Tumor limited to one subsite* of supraglottis with normal vocal cord mobility
• T2: Tumor invades mucosa of more than one adjacent subsite* of supraglottis or glottis or region outside the supraglottis (e.g., mucosa of base of tongue, vallecula, or medial wall of pyriform sinus) without fixation of the larynx
• T3: Tumor limited to larynx with vocal cord fixation and/or invades any of the following: postcricoid area, pre-epiglottic tissues, paraglottic space, and/or minor thyroid cartilage erosion (e.g., inner cortex)
• T4a: Tumor invades through the thyroid cartilage, and/or invades tissues beyond the larynx (e.g., trachea, soft tissues of the neck including deep extrinsic muscle of the tongue, strap muscles, thyroid, or esophagus)
• T4b: Tumor invades prevertebral space, encases carotid artery, or invades mediastinal structures

  Subsites include the following:

  • Ventricular bands (false cords)
  • Arytenoids
  • Suprahyoid epiglottis
  • Infrahyoid epiglottis
  • Aryepiglottic folds (laryngeal aspect)

 [Note: Supraglottis involves many individual subsites. Relapse-free survival may differ by subsite and by T and N groupings within stage.]

Glottis

• T1: Tumor limited to the vocal cord(s), which may involve anterior or posterior commissure, with normal mobility
  • T1a: Tumor limited to one vocal cord
  • T1b: Tumor involves both vocal cords
• T2: Tumor extends to supraglottis and/or subglottis and/or with impaired vocal cord mobility
• T3: Tumor limited to the larynx with vocal cord fixation and/or invades paraglottic space, and/or minor thyroid cartilage erosion (e.g., inner cortex)
• T4a: Tumor invades through the thyroid cartilage and/or invades tissues beyond the larynx (e.g., trachea, soft tissues of neck, including deep extrinsic muscle of the tongue, strap muscles, thyroid, or esophagus)
• T4b: Tumor invades prevertebral space, encases carotid artery, or invades mediastinal structures

 [Note: Glottic presentation may vary by volume of tumor, anatomic region involved, and the presence or absence of normal cord mobility. Relapse-free survival may differ by these and other factors in addition to T and N subgroupings within the stage.]

Subglottis

• T1: Tumor limited to the subglottis
• T2: Tumor extends to vocal cord(s) with normal or impaired mobility
• T3: Tumor limited to larynx with vocal cord fixation
• T4a: Tumor invades cricoid or thyroid cartilage and/or invades tissues beyond the larynx (e.g., trachea, soft tissues of neck, including deep extrinsic muscles of the tongue, strap muscles, thyroid, or esophagus)
• T4b: Tumor invades prevertebral space, encases carotid artery, or invades mediastinal structures

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 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

Evaluation of treatment outcome can be reported in various ways: locoregional control, disease-free survival, determinate survival, and overall survival at 2 to 5 years. Preservation of voice is an important parameter to evaluate. Outcome should be reported after initial surgery, initial radiation, planned combined treatment, or surgical salvage of radiation failures. Primary source material should be consulted to review these differences.

Because of clinical problems related to smoking and alcohol use in this population, many patients succumb to intercurrent illness rather than to the primary cancer.

Direct comparison of results of radiation versus surgery is complicated. Surgical studies can report outcome based on pathologic staging, whereas radiation studies must report on clinical staging, with the obvious problem of understaging in patients treated with radiation, particularly in the neck. In addition, radiation alone is often recommended for patients with poor performance status, which leads to less favorable results.

References

1. Thabet HM, Sessions DG, Gado MH, et al.: Comparison of clinical evaluation and computed tomographic diagnostic accuracy for tumors of the larynx and hypopharynx. Laryngoscope 106 (5 Pt 1): 589-94, 1996.  [PUBMED Abstract]
   
   
2. Larynx. In: American Joint Committee on Cancer.: AJCC Cancer Staging Manual. 6th ed. New York, NY: Springer, 2002, pp 47-57. 
   
   

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