Laryngeal Cancer: TNM Stage Systems

The staging system is 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 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]

TNM definitions

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, 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
    T4: Tumor invades through the thyroid cartilage, and/or extends into soft
         tissues of the neck, thyroid, and/or esophagus

*Subsites include the following:
     ventricular bands (false cords)
     arytenoids
     suprahyoid epiglottis
     infrahyoid epiglottis
     aryepiglottic folds (laryngeal aspect)

Glottis
    T1: Tumor limited to vocal cord(s) (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
    T4: Tumor invades through the thyroid cartilage and/or to other tissues
         beyond the larynx (e.g., trachea, soft tissues of neck, including
         thyroid, pharynx)

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
    T4: Tumor invades through cricoid or thyroid cartilage and/or extends to
         other tissues beyond the larynx (e.g., trachea, soft tissues of neck,
         including thyroid, esophagus)

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 less in greatest dimension
    N2: Metastasis in a single ipsilateral lymph node, more than 3 cm but
not more than 6 cm in greatest dimension, or in multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension, or in bilateral or         contralateral lymph nodes, none more than 6 cm in greatest dimension
           N2a: Metastasis in a single ipsilateral lymph node more than 3 cm
                 but not more than 6 cm in greatest dimension
           N2b: Metastasis in multiple ipsilateral lymph nodes, none more than
                 6 cm in greatest dimension
           N2c: Metastasis in bilateral or contralateral lymph nodes, none more
                 than 6 cm in greatest dimension
    N3: Metastasis in a lymph node more 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 centimeters in diameter are not single nodes but confluent nodes or tumors in soft tissues of the neck. There are 3 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

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

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 stage.

AJCC stage groupings

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
    T4, N0, M0
    T4, N1, M0
    Any T, N2, M0

Stage IVB
    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, leading 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): 589-594, 1996.
2. Larynx. In: American Joint Committee on Cancer: AJCC Cancer Staging Manual. Philadelphia, Pa: Lippincott-Raven Publishers, 5th ed., 1997, pp 41-46.