Seminars in Surgical Oncology 8:73-77 (1992)

Staging of Head and Neck Cancer

HARVEY W. BAKER, MD

From the Department of Surgery, Oregon Health Sciences University, Portland

Revised staging systems for cancers of the upper aerodigestive tract, the major salivary glands, and the thyroid are presented. The staging has been accepted by both the American Joint Committee on Cancer and the International Union Against Cancer and is gaining worldwide acceptance. 0 1992 Wiley-Liss, Inc.

KEY WORDS: upper aerodigestive tract, salivary glands, thyroid

INTRODUCTION Malignant tumors arising in the head and neck are of various histologic types occurring at a large number of anatomic sites and differing tremendously in extent. Systems for classification and staging have permitted a meaningful, valid grouping of these neoplasms, which is of great clinical importance. As therapeutic strategies have become more sophisticated, there is an increasing need for treatment planning based on the stage of the cancer. Staging is an essential tool for communication, permitting uniform reporting of inci- dence, treatment, and end results. It is also indispens- able in selecting similar subgroups of patients for col- laborative clinical trials.

In past years, staging systems have been developed and popularized by both the American Joint Commit- tee on Cancer (AJCC) [l] and the International Union Against Cancer (UTCC) [2]. While these systems were similar in many respects, there were significant differ- ences, which interfered with international communica- tion and cooperation. To remedy this problem, a series of meetings between the AJCC and the UICC from 1984 to 1986 resulted in the acceptance of uniform staging systems for cancers of the head and neck and other anatomic sites. These systems have been pub- lished [3] and have achieved worldwide acceptance.

The new staging systems were developed to elimi- nate differences in previous systems as well as errors or difficulties that had become apparent over the years. The systems are based on extensive medical records reviews as well as on the clinical experience of experts from many countries. The goal of the various groups engaged was to develop a staging system for each anatomic site that was simple, reproducible, and scien- tifically valid. This report presents the agreed upon staging systems for cancers of the upper aerodigestive

tract, the salivary glands, and the thyroid. It will in- clude the new TNM classifications as well as a discus- sion of some significant changes from previous sys- tems.

STAGING OF CANCER OF THE UPPER AERODIGESTIVE TRACT

These staging systems are applied to squamous cell carcinomas arising in the lining mucosa of the oral cavity, the pharynx (nasopharynx, oropharynx, hypo- pharynx), the larynx, and the maxillary sinus. The staging systems are all clinical staging (cTNM) based on the best possible estimate of the extent of the cancer before the first treatment. While pathologic staging (pTNM) based on both clinical information and ex- amination of the surgically resected specimen would be more accurate, it is of less practical importance in the management of these tumors since many of them are treated with radiation rather than surgery.

The Staging Process The diagnosis of squamous cell carcinoma must be confirmed by examination of a biopsy specimen; the histologic grade of the tumor is noted. While addi- tional biopsies of adjacent tissues or cervical lymph nodes may aid in clinical staging, they are not re- quired. A thorough regional examination is carried out to determine the extent of the primary tumor and of any cervical lymph node metastases. Visual exarni- nation and palpation alone may suffice to evaluate lesions of the oral cavity or oropharynx. Both indi- rect and direct endoscopy are required to evaluate cancers of the larynx, nasopharynx, and hypo- pharynx. These examinations may be supplemented

?Deceased 1991.

0 1992 Wiley-Liss, Inc.

74 Baker

by a number of radiologic techniques, which are becoming ever more sophisticated and are of particu- lar value in determining the extent of less accessible neoplasms. A routine chest roetgenogram and blood chemistry studies (including serum calcium levels) are obtained. The patient’s symptoms, abnormal test re- sults, or research protocols may indicate further di- agnostic studies. The patient’s performance status is noted. Some clinicians advocate panendoscopy (di- rect laryngoscopy, bronchoscopy, and esophagos- copy) for all cancers of the upper aerodigestive tract. While not required for staging, this procedure may identify another primary cancer, which is not uncom- mon in this group of patients.

The T categories represent the best estimate of the extent of the primary tumor. While they are roughly comparable, it is impossible to assign identical T cate- gories to each anatomic site. Accessible tumors in the oral cavity and oropharynx are readily measured, but tumors in other locations are more difficult to mea- sure, and their T categories reflect extension to neigh- boring structures or impaired mobility. The most ac- curate prognostic characteristic of a primary tumor is the depth of invasion, but this factor unfortunately cannot be utilized for clinical staging. Terms such as superficial or deeply invasive are subjective and may vary from one examiner to another and interfere with reproducible staging. In this revised staging system, the T4 categories for cancers of the lip and oral cavity have been made more specific; other T categories have remained essentially unchanged.

Significant changes have been made in the N catego- ries, which are identical for all cancers of the upper aerodigestive tract. Bilateral cervical node metastases, previously classified as N3 by the AJCC, were changed to N2 as suggested by the UICC in view of their some- what more favorable prognosis with current therapy. The termjxed, previously used by the UICC to assign nodes to the N3 category, was abandoned because the degree of fixation can vary and is prone to subjective interpretation by different observors. It was replaced by the AJCC definition of N3 as a node 6 cm or more in greatest diameter. While capsular invasion of a lymph node and extranodal extension are of consider- able prognostic importance, these findings cannot be included in clinical staging. They are, however, often suggested by the size of the cervical mass, which is included in the staging process.

Oral Cavity The oral cavity extends from the skin-vermillion junc- tion of the lips anteriorly to the junction of the hard and soft palates above and the line of the circumval- late papillae of the tongue below. It includes the lips,

TABLE I. T Categories for Cancer of the Oral Cavity

T, T,

T, T,

Tumor 2 cm or less in greatest dimension Tumor more than 2 cm but not more than 4 cm in greatest

Tumor more than 4 cm in greatest dimension L@: Tumor invades adjacent structures, eg, through

Oral cavity: Tumor invades adjacent structure, eg, through

dimension

cortical bone, tongue, skin of neck

cortical bone, into deep (extrinsic) muscle of tongue, maxillarv sinus. skin.

buccal mucosa, upper and lower alveolar ridges and retromolar gingiva (retromolar trigone), floor of the mouth, hard palate, and anterior two-thirds of the tongue. The T categories for the oral cavity are de- scribed in Table I.

Pharynx The pharynx is divided into three regions: nasophar- ynx, oropharynx, and hypopharynx. Each region is divided into a number of specific subsites. The naso- pharynx includes the posterior wall and the superior wall (vault); the lateral walls, which contain the eusta- chian tube orifices; and the inferior wall, which con- sists of the superior surface of the soft palate. The oropharynx includes the faucial arches (soft palate, uvula, and anterior tonsillar pillars), the tonsillar fossa and tonsil, the base of the tongue, and the lateral and posterior pharyngeal walls. The hypopharynx is com- posed of the piriform sinuses, the postcricoid area, and the posterior hypopharyngeal wall. T categories for the pharynx are listed in Table 11.

Larynx The larynx is divided into three regions: the supraglot- tis, the glottis, and the subglottis. The supraglottis includes the ventricular bands (false cords), the ary- tenoids, the epiglottis (both lingual and laryngeal as- pects), and the aryepiglottic folds. The glottis is com- posed of the true vocal cords, with their anterior and posterior commissures. The subglottis extends from the lower margin of the glottis to the lower margin of the cricoid cartilage. T categories for the larynx are listed in Table 111.

Maxillary Sinus Ohngren’s line, a theoretical plane between the medi- cal canthus of the eye and the angle of the mandible, divides the maxillary sinus into an anteroinferior por- tion (the infrastructure) and a posterosuperior portion (the suprastructure). The T categories for cancers of the maxillary sinus are listed in Table IV. Staging systems for less common tumors of other paranasal sinuses and the nasal cavity have not yet been devel- oped.

TABLE 11. T Categories for Cancer of the Pharvnx

Head and Neck Cancer Staging 75

TABLE 111. T Categories for Cancer of the Larvnx

Nasopharynx

Tumor limited to one subsite of nasopharynx

Tumor invades more than one subsite of nasopharynx

Tumor invades nasal cavity andlor oropharynx

Tumor invades skull andlor cranial nerves

Oropharynx Hypopharynx

Tumor 2 cm or less in greatest dimension

Tumor more than 2 cm but not more than 4 cm in greatest dimension

Tumor more than 4 cm in greatest dimension

Tumor invades adjacent structures, e.g., through cortical bone, soft tissue of neck, deep (extrinsic) muscle of tnnmw

Tumor limited to subsite of hypopharynx

Tumor invades more than one subsite or adjacent area without fixation of hemilarynx

Tumor invades more than one subsite or adjacent area with fixation of hemilarynx

Tumor invades adjacent structures, e.g., cartilage or soft tissues of neck

Cervical Lymph Node Metastases (Table V) The N categories for cancers in all sites of the upper aerodigestive tract are identical. The actual size of the nodal mass is measured, and allowance is made for intervening soft tissues. Midline nodes are considered ipsilateral nodes. It is recognized that most masses larger than 3 cm are not single nodes but represent confluent nodes or tumor extension into soft tissues.

Distant Metastases (Table VI) Distant spread to the lungs is common for this group of tumors. Skeletal or hepatic metastases occur less often. Mediastinal lymph node metastases are consid- ered distant spread.

Stage Grouping (Table VII) Once the T, N, and M categories have been deter- mined, the tumor is assigned to one of four stages. The stages are similar for squamous cell carcinomas at all sites in the upper aerodigestive tract and correlate quite closely with the prognosis.

STAGING FOR CANCER OF THE SALIVARY GLANDS

The following staging system is applicable to all malig- nant tumors of the major salivary glands: the parotid,

Supraglottis

Tumor limited to one subsite of supraglottis with normal vocal cord mobility

Tumor invades more than one subsite of supraglottis or glottis with normal cord mobility

Tumor limited to larynx with vocal cord fixation andlor invades postcriocoid area, piriform sinus, or preepiglottic space

Tumor extends through thyroid cartilage andlor extends to other tissues beyond the larynx, e.g., oropharynx, soft tissues of neck

Glottis

Tumor limited to vocal cord(s), (may involve anterior or posterior commissures) with normal mobility.

Tumor extends to supraglottis and/or subglottis andlor with impaired cord mobility

Tumor limited to the larynx with vocal cord fixation

Tumor extends through thyroid cartilage andlor extends to other tissues beyond the larynx, e.g., oropharynx, soft tissues of neck

Subglottis

Tumor limited to the subglottis

Tumor extends to vocal cord(s) with normal or impaired mobility

Tumor limited to the larynx with vocal cord fixation

Tumor' invades through cricoid or thyroid cartilages andlor extends to other tissues beyond the larynx, e.g., oropharynx, soft tissues of neck

TABLE IV. T Categories for Cancer of the Maxillary Sinus

TI

T,

T,

Tumor limited to the antral mucosa with no erosion or

Tumor with erosion or destruction of the infrastructure,

Tumor invades any of the following: skin of cheek,

destruction of bone

including the hard palate and/or the middle nasal meatus

posterior wall of maxillary sinus, floor or medial wall of orbit, anterior ethmoidal sinus

Tumor invades orbital contents and/or any of the following: cribriform plate, posterior ethmoidal or sphenoidal sinuses, nasopharynx, soft palate, utervpomaxillarv or temDoral fossae. base of skull

Td

submaxillary, and sublingual. It does not apply to tumors of the minor salivary glands, that is, mucus secreting glands of the lining of the upper aerodiges- tive tract. While clinical staging is possible after the diagnosis has been confirmed by biopsy, pathologic staging is most frequently used for these tumors.

76 Baker

The Staging Process The essential procedures for pathologic staging of sali- vary gland cancer include a careful physical examina- tion, chest roentgenogram, blood chemistry studies, report of the operative findings, and gross and micro- scopic examination of the operative specimen. The size of the primary tumor, its degree of fixation to surrounding structures, and evidence of cervical lymph node involvement are recorded. Any clinical involvement of the facial, hypoglossal, or adjacent sensory nerves should be noted. Some bulkey or fixed tumors require radiographic studies of the mandible for full evaluation. Pathologic studies should include the histologic type and grade of the tumor, gross or microscopic extension into adjacent tissues, and evi- dence of cervical lymph node metastasis. Symptoms or suspicious clinical findings may suggest additional staging studies such as computed tomography (CT) scans of the chest or radionuclide studies of bone. A sialogram is seldom useful as a staging measure. The patient's performance status should be recorded, par- ticularly when retreatment staging is required.

Table VIII lists the T categories for salivary gland cancers. Tumor size and local extension are the signif- icant parameters. Local extension is defined as clinical or macroscopic evidence of invasion of skin, soft tis- sues, nerve, or bone. In the previous staging system, local extension of any salivary gland cancer automati- cally placed it in a T4b category. Review of survival data has revealed that local extension is far less omi- nous in smaller tumors than in larger ones. In this

TABLE V. N Categories for Cancer of the Upper Aerodigestive Tract and Salivary Glands

No regional lymph node metastases Metastasis in a single ipsilateral regional node 3 cm

Metastasis in a single ipsilateral node more than 3

NO N,

or less in greatest dimension

cm but not more than 6 cm in greatest dimension: or multiple ipsilateral nodes. none more than 6 cm in greatest dimension; or bilateral or contralateral nodes, none more than 6 cm in greatest dimension

cm but not more than 6 cm in greatest dimension

than 6 cm in greatest dimension

more than 6 cm in greatest dimension

greatest dimension

Nz

N,a

NZb

Nzc

Metastasis in a single ipsilateral node more than 3

Metastasis in multiple ipsilateral nodes, none more

Metastasis in bilateral or contralateral nodes. none

Metastasis in a lymph node more than 6 cm in N,

TABLE VI. M Categories for Cancer of the Upper Aerodigestive Tract

Presence of distant metastasis cannot be be assessed No distant metastasis Distant metastasis

Mx MO M ,

revised staging system, the presence or absence of local extension is indicated as a suffix to each T category, representing the size of the tumor. Arrangement of tumors in this revised system correlates far more closely with observed 5 year survival rates. Micro- scopic evidence alone is not considered local extension for staging purposes. The N categories for salivary gland cancers are the same as those for cancers of the upper aerodigestive tract (Table V), as are the M cate- gories (Table VI). Stage groupings for salivary gland cancers are listed in Table IX.

STAGING OF CANCER OF THE THYROID Although staging of other cancers of the head and neck is based entirely on the anatomic extent of dis- ease, this pattern is not possible for the unique group of malignant tumors of the thyroid gland. This histo- logic diagnosis and the patient's age are such impor- tant factors that they must be included in any staging system. Although clinical staging is possible after bi- opsy diagnosis, pathologic staging furnishes the

TABLE VII. Stage Grouping for Cancer of the Upper Aerodigestive Tract

Stage I TINOM, Stage 11 T,NoMo Stage 111 T3NoMo

T I , T,, or T, N , M"

Stage IV T4No or N,M, Any T N, or N,M, Any T Any N MI

TABLE VIII. T Categories for Cancer of the Salivarv Glands*

TI T,

T,

T, *All categories are subdivided into a, no local extension; b, local extension. Local extension is clinical or macroscopic evidence of invasion of skin, soft tissues, bone, or nerve.

Tumor 2 cm or less in greatest dimension Tumor more than 2 cm but not more than 4 cm in greatest

Tumor more than 4 cm but not more than 6 cm in greatest

Tumor more than 6 cm in greatest dimension

dimension

dimension

TABLE IX. Stage Group for Cancer of the Salivary Glands

Stage I

Stage 11

Stage 111

Stage IV T 4 b Any T N, or N, Mo Any T Any N M I

Head and Neck Cancer Staging 77

greatest amount of evaluative evidence and is most useful.

The Staging Process The essential studies for staging thyroid cancer begin with physical examination of the thyroid and regional lymph nodes. The size, consistency, and mobility of the thyroid mass and enlarged nodes are recorded. Indirect laryngoscopy to evaluate vocal cord motion is important. A chest roentgenogram and blood chemis- try studies should be included. A variety of imaging studies including radioisotope thyroid scans, CT scans, and magnetic resonance (MR) scans and ul- trasound examinations may be helpful. Needle biopsy

TABLE X. T Categories for Cancer of the Thyroid*

To No evidence of primary tumor T, Tumor 1 cm or less in greatest dimension limited to the

T, Tumor more than 1 cm but not more than 4 cm in greatest

T, Tumor more than 4 cm in greast dimension limited to the

T4 Tumor of any size extending beyond the thyroid capsule *Each category is divided into a, solitary tumor; b, multifocal tumor (measure the largest for classification).

thyroid

dimension limited to the thyroid

thyroid

TABLE XI. N Categories for Cancer of the Thyroid

No No regional lymph node metastasis N, Regional lymph node metastasis

NIa To ipsilateral cervical node(s) N,, To bilateral, contralateral, or midline cervical or

mediastinal node(s)

TABLE XII. Staging Grouping for Cancer of the Thyroid

Papillary or follicular Age under Age 45 years carcinoma 45 years and over

Stage I Any T Any N M, TI No M, Stage I1 Any T Any N M, T, No M, Stage 111 T3 No Mo

T4 No Mo Stage IV

Medullary carcinoma All ages

Any T N, M, Any T Any N MI

Stage I TI No Mo Stage 11 Stage I11 Stage IV

Undifferentiated carcinoma All ages

T,, T,, or T, No M, Any T N, M, Any T Any N MI

All cases are considered Stage IV

or open biopsy of the thyroid mass or enlarged cervical nodes is used for diagnosis when clinical staging alone is required. Pathologic staging utilizes all of the above data plus the operative report and pathologic examination of all surgically resected tissues.

In previously published AJCC staging systems for thyroid cancer, the stages for each histologic group were separated into ages under 45 years and ages 45 years and over. The separation for age groups in the new system applies only to the well-differentiated pap- illary and follicular tumors. Age has seemed of less prognostic significance in the more aggressive thyroid neoplasms.

Table X lists the T categories for thyroid cancer and Table XI the N categories. The M categories are the same as for other head and neck cancers (Table VI). Table XI1 lists the stage groupings for thyroid cancer and allows for prognostic differences for the various histologic types as well as age differences for the well- differentiated tumors.

DISCUSSION Current staging systems for head and neck cancer rec- ommended by the AJCC and the UICC have been presented. Changes in familiar staging systems are al- ways upsetting to clinicians, tumor registrars, and medical record librarians. In the light of continued experience and advancing knowledge, however, such changes are inevitable. Continuing studies will no doubt identify further faults or areas of weakness in the current systems. A notable advance has been the willingness of the AJCC and the UICC to adopt iden- tical systems for worldwide use. Both organizations have agreed to keep the interval between changes as long as possible, hopefully 10 years or more.

While present staging systems are based primarily on the anatomic extent of disease, other factors identi- fied in recent studies may be of equal or even greater prognostic significance. These factors include the state of the host immune system as it is measured by an increasing number of parameters. They also include the biologic potential of the cancer cell as evidenced by DNA content, ploidy, doubling time, etc. Such factors may eventually be included in a meaningful staging system for many cancers.

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2 . International Union Against Cancer: “TNM Classification of

3. American Joint Committee on Cancer: “Manual for Staging of

Cancer, 2nd ed.” Philadelphia: J.B. Lippincott Co., 1983.

Malignant Tumors.” Geneva: IUAC, 1982.

Cancer, 3rd ed.” Philadelphia: J.B. Lippincott Co., 1988.