Laryngeal cancer - Classification

Modern classifications of laryngeal cancer are based on the localization, stage of development and histological structure of the tumor. Of the various forms of laryngeal cancer, squamous cell is found in 95%, glandular - in 2%, basal cell - in 2%, other forms - in 1% of cases. The form of tumor growth is divided into exophytic (into the laryngeal cavity), endophytic (into the thickness of the laryngeal tissue) and mixed. From a practical point of view, according to the topographic principle, laryngeal cancer can be classified as follows:

1. cancer of the upper larynx (vestibular cancer, cancer supragloticum), localized on the posterior surface of the epiglottis, in the pre-epiglottic space, in the aryepiglottic folds and other parts of the vestibule of the larynx;
2. cancer of the middle part of the larynx (cancer gloticum), affecting the vocal folds and the area of the anterior commissure;
3. cancer of the lower part of the larynx (cancer subgloticum), which covers the tissues of the subglottic space to the lower edge of the cricoid cartilage.

Vestibular cancer, having arisen on one side, very quickly affects the opposite side and grows into the pre-glottic space. Cancer arising in the ventricles of the larynx quickly prolapses into the lumen of the larynx, causing a violation of voice formation and breathing. Cancers of the middle part of the larynx are the most common and are localized at the initial stage exclusively in one vocal fold - cancer in situ. The vocal disorders caused by this form of cancer contribute to its early diagnosis, therefore, the prognosis for this form is the most favorable. This is also facilitated by the fact that vocal fold cancer remains unilateral for a long time and very late spreads to other areas of the larynx. Cancer of the subglottic space usually refers to tumors of infiltrative growth and very quickly spreads to the opposite side, affecting the anterior commissure and both vocal folds.

The lower border of subglottic cancer is most often limited by the lower edge of the thyroid cartilage, but in its development this form of cancer can descend to the lower border of the cricoid cartilage, and in advanced cases, move to the tracheal rings.

The spread of laryngeal cancer is prevented by obstacles in its path in the form of ligaments and muscles of the larynx, and this spread is facilitated by lymphatic vessels, which, however, also have their own barrier in the form of vocal folds, where they are greatly reduced. The superior supraglottic lymphatic vessels are connected with the anatomical formations of the vestibule of the larynx (epiglottis, aryepiglottic folds, ventricles of the larynx). Collecting lymph from these formations, the lymphatic vessels, penetrating the lateral part of the thyrohyoid membrane, flow into the superior jugular lymph nodes, where they carry metastases from the corresponding areas.

The inferior lymphatic network collects lymph from the anatomical structures of the subglottic space; it forms two outflow pathways: one of them (anterior), penetrating the cricothyroid membrane, flows into the pre- and peritracheal, as well as the inferior jugular lymph nodes; the other pathway (posterior), penetrating the cricotracheal membrane, flows into the lymph nodes of the recurrent nerves and from there into the inferior jugular nodes.

The median region of the lymphatic vascular network is represented by a small number of very thin vessels located along the vocal folds and weakly anastomosing with the upper and lower lymphatic vascular networks, which explains the rare and late metastasis from this region to the above-mentioned lymph nodes.

Metastases to distant organs in laryngeal cancer are not so common: 4% - to the lungs, 1.2% - to the esophagus, liver, bones; even less often - to the stomach, intestines and brain.

In practice, the international classification of laryngeal cancer according to the TNM system (6th edition, 2002) is widely used.

Primary tumor (T):

• T - primary tumor;
• Tx - insufficient data to assess the primary tumor;
• T0 primary tumor is not detected;
• Tis preinvasive carcinoma (carcinoma in situ).

Vestibular section:

• T1 - the tumor is limited to one anatomical region of the vestibular region, the mobility of the vocal folds is preserved.
• T2 - the tumor affects the mucous membrane or several anatomical parts of the vestibular region or one part of the vestibular region and one or several parts of the vocal folds, the mobility of the vocal folds is preserved:
• T3 - the tumor is limited to the larynx with fixation of the vocal folds and/or spread to the retrocricoid region or preepiglottic tissues:
• T4a - the tumor spreads to the thyroid cartilage and/or other tissues adjacent to the larynx: trachea, thyroid gland, esophagus, soft tissues of the neck, including deep muscles (genioglossus, hyoglossus, palatoglossus and styloglossus), infrahyoid muscles;
• T4b - the tumor extends into the prevertebral space, mediastinal structures, or involves the carotid artery.

Vocal fold area:

• T1 - the tumor is limited to the vocal folds without impaired mobility (the anterior or posterior commissures may be involved);
  • T1a - the tumor is limited to one fold;
  • T1b - the tumor affects both ligaments;
• T2 - the tumor extends to the vestibular and/or subglottic region, and/or the mobility of the vocal folds is impaired:
• T3 - the tumor is limited to the larynx with fixation of the vocal folds and/or damage to the periglottic space and/or damage to the thyroid cartilage (inner plate);
• T4a - the tumor spreads to the thyroid cartilage and/or tissues adjacent to the larynx: trachea, thyroid gland, esophagus, soft tissues of the neck, muscles of the tongue, pharynx.
• T4b - the tumor extends into the prevertebral space, mediastinal structures, or involves the carotid artery.

Sub voice area:

• T1 - the tumor is limited to the subglottic region;
• T2 - the tumor extends to one or both vocal folds with free or limited mobility;
• TZ - the tumor is limited to the larynx with fixation of the vocal fold;
• T4a - the tumor spreads to the cricoid or thyroid cartilage and/or to the tissues adjacent to the larynx: trachea, thyroid gland, esophagus, soft tissues of the neck;
• T4b - the tumor extends into the prevertebral space, mediastinal structures, or involves the carotid artery.

Regional lymph node involvement (N):

• Nx - insufficient data to assess regional lymph node involvement;
• N0 - no signs of damage to regional lymph nodes:
• N1 - metastases in one lymph node on the affected side up to 3 cm in greatest dimension;
• N2 - metastases in one or more lymph nodes on the affected side up to 6 cm in greatest dimension or metastases in the lymph nodes of the neck on both sides or on the opposite side up to 6 cm in greatest dimension;
  • N2a - metastases in one lymph node on the affected side up to 6 cm in greatest dimension;
  • N2b - metastases in several lymph nodes on the affected side up to 6 cm in greatest dimension;
• N2c - metastases in several nodes of the neck on both sides or on the opposite side up to 6 cm in the largest dimension;
• N3 - metastases in lymph nodes more than 6 cm in greatest dimension.

Distant metastases (M):

• Mx - insufficient data to determine distant metastases;
• M0 - no signs of distant metastases;
• M1 - there are distant metastases.

Histopathological differentiation (G):

• GX - the degree of differentiation cannot be determined;
• G1 - high degree of differentiation;
• G2 - average degree of differentiation;
• GЗ - low degree of differentiation;
• G4 - undifferentiated tumors.

Pathological classification (pTNM). Categories pT, pN, pM correspond to categories T, N and M of the international classification. The material obtained during partial cervical lymph node dissection should contain at least 6 lymph nodes. The material obtained during radical lymph node dissection should contain at least 10 lymph nodes for morphological examination.

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