RULES FOR CLASSIFICATION
DEFINITION OF TNM
HISTOPATHOLOGIC GRADE (G)
Manual for Staging of Cancer; Fifth Edition; Edited by Irvin D. Fleming, M.D., Jay S. Cooper, M.D., Donald Earl Henson, M.D., Robert V.P. Hutter, M.D., B.J. Kennedy, M.D., Gerald Murphy, M.D., D.S.c., Brian O'Sullivan, M.B., F.R.C.P.C., F.R.C.P.I., Leslie H. Sobin, M.D., John W. Yarbro, M.D., Ph.D.; Copyright 1997, the American Joint Committee on Cancer. Published by Lippincott-Raven Publishers. Chapter 5, pp. 41 - 46.
|C10.1||Anterior (lingual) surface of epiglottis|
|C32.1||Supraglottis (laryngeal surface)|
The anterior limit of the larynx is composed of the anterior or lingual surface of the suprahyoid epiglottis, the thyrohyoid membrane, the anterior commissure, and the anterior wall of the subglottic region, which is composed of the thyroid cartilage, the cricothyroid membrane, and the anterior arch of the cricoid cartilage.
The posterior and lateral limits include the laryngeal aspect of aryepiglottic folds, the arytenoid region, the interarytenoid space, and the posterior surface of the subglottic space, represented by the mucous membrane covering the surface of the cricoid cartilage.
The superolateral limits are composed of the tip and the lateral borders of the epiglottis. The inferior limits are made up of the plane passing through the inferior edge of the cricoid cartilage.
For purposes of this clinical stage classification, the larynx is divided into three regions: supraglottis, glottis, and subglottis. The supraglottis is composed of the epiglottis (both its lingual and laryngeal aspects), aryepiglottic folds (laryngeal aspect), arytenoids, and ventricular bands (false cords). The epiglottis is divided for staging purposes into suprahyoid and infrahyoid positions by a plane at the level of the hyoid bone. The inferior boundary of the supraglottis is a horizontal plane passing through the lateral margin of the ventricle at its junction with the superior surface of the vocal cord. The glottis is composed of the true vocal cords, including the anterior and posterior commissures, superior and inferior surfaces. It occupies a horizontal plane, 1 cm in thickness, extending inferiorly from the lateral margin of the ventricle. The subglottis is the region extending from the lower boundary of the glottis to the lower margin of the cricoid cartilage.
The division of the larynx is summarized in the following table:
|Aryepiglottic folds (laryngeal aspect)|
|Ventricular bands (false cords)|
|Glottis||True vocal cords including anterior and posterior commissures|
Regional Lymph Nodes. The incidence and distribution of cervical nodal metastases from cancer of the larynx varies with the site of origin and the "T" classification of the primary tumor. The true vocal cords are nearly devoid of lymphatics and tumors of that site alone rarely spread to regional nodes. On the contrary, the supraglottis has a rich and bilaterally interconnected lymphatic network and primary supraglottic cancers are commonly accompanied by regional nodal spread. Glottic tumors may spread directly to adjacent soft tissues and pre laryngeal, pretracheal, paralaryngeal and paratracheal nodes as well as upper, mid and lower jugular nodes. Supraglottic tumors commonly spread to upper and midjugular nodes, considerably less commonly to submental or submandibular nodes, but occasionally to retropharyngeal nodes. The rare subglottic primary tumors spread first to adjacent soft tissues and prelaryngeal, pretracheal, paralaryngeal and para tracheal nodes, then to mid and lower jugular nodes. Contralateral lymphatic spread is common.
In clinical evaluation the physical size of the nodal mass should be measured. It is recognized that most masses over 3 cm in diameter are not single nodes but are confluent nodes or tumor in soft tissues of the neck. There are three categories 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 ipsilateral nodes. In addition to the components to describe the N-category, regional lymph nodes should also be described according to the level of the neck that is involved. Pathologic examination is necessary for documentation of such disease extent. Imaging studies showing amorphous spiculated margins of involved nodes or involvement of internodal fat resulting in loss of normal oval-to-round nodal shape strongly suggest extracapsular (extranodal) tumor spread. No imaging study (as yet) can identify microscopic foci in regional nodes or distinguish between small reactive nodes and small malignant nodes without central radiographic inhomogeneity.
For pN, a selective neck dissection will ordinarily include 6 or more lymph nodes and a radical or modified radical neck dissection will ordinarily include 10 or more lymph nodes.
Metastatic Sites. Distant spread is common only for patients who have bulky adenopathy. When distant metastases occur spread to the lungs is most common; skeletal or hepatic metastases occur less often. Mediastinal lymph node metastases are considered distant metastases.
Complete endoscopy, usually under general anesthesia, is generally performed after completion of other diagnostic studies to accurately assess, document and biopsy the tumor.
Pathologic Staging. All information used in clinical staging and in histologic studies of the surgically resected specimen is used for pathologic staging. The surgeon's evaluation of gross unresected residual tumor must also be included. The pathologic description of any lymphadenectomy specimen should describe the size, number, and level of involved lymph nodes.
Primary Tumor (T)
|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|
|T1||Tumor limited to the 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)|
|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)|
|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|
Continued exposure to carcinogens, such as alcohol and tobacco smoke, likely also affects patients' outcome adversely.
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