Core Curriculum Syllabus: Head and Neck Tumors
The management of cancers of the head and neck has conventionally been the province of surgeons and radiotherapists. In the past fifteen years, medical oncologists have been increasingly involved in patients with these neoplasms. Multimodality management of head and neck cancer patients is now the modus operandi in most medical centers. Head and neck tumors should not only be the concern of head and neck surgeons, radiotherapists and oncologists, but also all primary care physicians and dentists. Practitioners familiar with these tumors can often recognize the symptoms and signs of early disease. The establishment of a diagnosis of head and neck cancer at an early stage significantly improves the prospect of curative therapy.
Incidence and Epidemiology
- Squamous cancers of the upper aerodigestive tract constitute approximately 6% of new cancer cases in men and 2% of women. At all sites, except the salivary glands, there is a significant preponderance of cases in men. Oral and pharyngeal cancer is more common in white males at every site, but the incidence of laryngeal cancer is somewhat higher in black males.
- The geographic distribution pattern for head and neck cancer shows considerable variation and is site-dependent. For example, cancers of the nasal cavity and paranasal sinuses are slightly more common in the South than in the rest of the United States. Nasopharyngeal cancer is a very common disease in the Chinese, with age-specific incidence rates in males from Kwangtung Province (Cantonese) 40 times that of U.S. Caucasian males.
Etiology and Pathogenesis
- The overwhelming majority of head and neck cancers have been related to prolonged exposure to environmental factors. While many associations between risk factors and various head and neck cancers are firm, others remain questionable.
- Sunlight - Lip cancer, skin cancer
- Tobacco - Tobacco contains many carcinogens
- Risk is a function of the degree of exposure and the inherent susceptibility of the site. Tobacco chewing is uncommon in the United States. However, it is common practice in some parts of the world, such as Ceylon, Bombay, other parts of India and portions of Southeast Asia, which have some of the highest incidence rates in the world of oral and pharyngeal cancer. Oral cavity cancer is the commonest form of cancer in Bombay. A mixture called pan (betel, nut and leaf, lime, catechu, tobacco and other additives) is very popular in India. It is chewed into a quid and buccal mucosa cancer usually develops at the site where the quid is kept and has most frequent contact.
- Further evidence of the importance of type of exposure and site of cancer is the high incidence of cancer of the hard palate in populations that practice reverse smoking, i.e., where the burning end of the cigarette is kept in the mouth during smoking, in parts of India, Sardinia, Venezuela and Panama. Hard palate cancer is otherwise uncommon in most of the world.
- Cancer of the lip associated with pipe smoking.
- Cigarette smoking, the most popular form of tobacco use in this country clearly plays a causative role in tongue, pharyngeal, laryngeal, esophageal and lung cancer.
- Synergistic with tobacco
- Ethanol per se, not a carcinogen, other factors implicated
- Nutritional Deficiencies - Specific role not established, but an area of increasing study and investigation
- Occupational Factors - e.g., nickel workers, wood workers implicated in paranasal sinus cancer
- Epstein-Barr Virus (EBV) - Possible etiological role in nasopharyngeal carcinoma
- Genetic Factors - An area of increasing study and interest. Certainly, some families have high incidence of cancer but genetic link not completely understood. However, some head and neck neoplasms have had recent chromosomal identification, e.g., retinoblastoma linked to q14 band of chromosome 13, medullary carcinoma of thyroid to chromosome 10, neurofibromatosis to chromosome 22.
- Poor Oral Hygiene - Oral cavity, especially floor of mouth cancer, tongue, and alveolar ridge neoplasms.
- Radiation - Ionizing radiation which was used in past to treat such benign conditions as acne, tonsillar and adenoid hypertrophy, enlarged thymus in newborn and chronic sialoadenitis has led to increased risk of thyroid cancer, parotid neoplasms, malignant degeneration of papillomas and possibly other upper aerodigestive tract neoplasms.
Pathology Ulcerative or Exophytic
- Majority are squamous cell carcinoma (> 90%)
- Verrucous carcinoma
- Modes of Spread
- Epidermoid carcinomas of the head and neck usually remain localized and tend to progressively invade adjacent tissues.
- Extension into regional lymph nodes are more likely in lesions with:
- Large size
- Sites with abundant lymphatic drainage
- Hematogenous metastases-less common-seen in more aggressive tumors, and tumors present for some time
- Symptoms and Signs - Reflect the anatomic location, the degree of advancement and growth characteristics
- An obvious lesion
- Malodorous breath
- Otalgia - local or referred
- Trismus to muscles of mastication
- Nasal stuffiness, unilateral nasal obstruction, postnasal drip, headache and epistaxis should not be attributed to sinusitis without careful investigation
- Nasal speech
- "Hot potato" voice
- Poorly fitting dentures
- Loosening of teeth
- Cranial nerve palsies
- Cervical adenopathy - in patient with known head and neck primary malignancy, approximately 85% are metastatic
Most head and neck cancers are treatable and curable when discovered early. However, many cancers of the head and neck are large and extensive when diagnosed.
- Occupational risks and social habits
- Symptoms and signs
- Physical Examination
- Head and Neck Examination - both inspection and palpation especially oral cavity, base of the tongue, and palate
- General Physical Examination - distant metastases, coexisting medical problems
- Radiographic and Laboratory Studies
- Chest roentgenogram, complete blood count and platelet count, prothrombin time, partial thromboplastin time, SMA15, urinalysis and electrocardiogram
- Radionuclide scanning utility is dependent upon the likelihood of metastatic disease
- Biopsy - histologic confirmation of the diagnosis is mandatory before proceeding with any definite therapy
- Superficial lesions - punch biopsy - ideal for readily accessible lesions of the skin or mucosa
- Deeper lesions
- Needle biopsy
- Fine needle aspiration with cytology
- Large bore needle
- Incisional biopsy - violates capsule and potentially seeds tumor. Useful when all diagnostic modalities have failed to establish a diagnosis and excisional biopsy of the mass is not technically feasible.
- Excisional biopsy - removal of a suspected tumor mass in its entirety. Rarely indicated in squamous cell carcinomas of the upper aerodigestive tract.
- Evaluation of the Neck Mass - any neck mass in an adult that persists more than four to six weeks should be considered potentially malignant until proven otherwise, especially in patients with a history of smoking, drinking or neck radiation. The proper evaluation of this particular patient does not consist of immediate open neck biopsy, but begins with a complete physical examination with an emphasis on the head and neck. Appropriate blood studies and radiographs should be carried out. If complete examination of the head and neck does not reveal a primary lesion, then the patient should undergo endoscopy under general anesthesia. He should have nasopharyngoscopy, direct laryngoscopy, bronchoscopy, and esophagoscopy performed. In most instances, a primary lesion will be identified at the time of endoscopy and appropriate biopsies can be taken. A treatment plan can then be outlined based on the information obtained at endoscopy. In a small percentage of patients, no primary lesion will be grossly evident. Selected random biopsies should be performed of the nasopharynx, pyriform sinus, base of tongue, and tonsillar fossa, as these areas have been identified in previous studies as the most common sites for occult head and neck primaries. With this careful systematic evaluation, the primary tumor will be identified in almost all cases. However, in a small percentage of cases, no primary lesion will be found. If this is the case, then exploration of the neck with biopsy of the mass is indicated. The patient should be prepared for a neck dissection which is indicated if frozen section analysis reveals squamous carcinoma. In the case of adenocarcinoma or lymphoma, then a neck dissection is not performed and further diagnostic work-up and definitive therapy should be pursued.
The most commonly accepted staging in the United States is that of the American Joint Committee for Cancer Staging and End Results Reporting.
Specific and Supportive Management
- General Consideration of Specific Therapy for Various Stages of Disease - Choice of treatment should be based on the histopathology of the tumor, the staging classification of the tumor, the general physical status of the patient and the psychosocial condition of the patient at the time of diagnosis. These considerations will determine whether treatment should be directed at cure or palliation or simply support. Any treatment employed may affect respiration, deglutition, phonation and aesthetic appearance. It is important that the patient be an informed and active participant in treatment decisions throughout the course of therapy. The patient's ultimate decision should be respected at all times. By the same token, the patient should be made aware of the consequences of failing to pursue active treatment.
- The principles of therapy of head and neck cancer directed at cure of the disease should try to meet three objectives:
- To eradicate the neoplasm completely
- To give the patient the best functional result by careful planning of the radiation fields or appropriate reconstructive techniques for surgical defects
- To leave the patient with as good a cosmetic result as possible
- Principles of Palliation Therapy. In cancers which are deemed unresectable because of local extension or deemed incurable because of diffuse metastatic spread, treatment can be directed toward palliation.
- Palliative treatment may be employed to:
- Control local advancement of tumor
- Provide relief from pain, e.g., the use of radiotherapy for bone metastasis can be quite helpful in relieving the extreme pain incurred from such metastases
- Provide relief from obstruction, e.g., a patient with a far advanced laryngeal tumor may benefit greatly from a tracheostomy to prevent suffocation
- To control bleeding
- Palliative treatment may be employed to:
- Concern for the patient's quality of life should guide the treatment decisions. The choice of treatment modalities will depend on:
- The size of the tumor and the location of the lesion
- The gross characteristics of the tumors, i.e., exophytic or infiltrative
- Histopathologic differentiation of the tumor
- Presence of local bone and muscle involvement
- Presence or absence of nodal disease
- The general medical condition of the patient
- Socio-economic condition and occupation of the patient
- The experience of the surgeon, radiotherapist and oncologist in treating head and neck tumors
The tools at the disposal of the radiotherapist, the surgeon, and the medical oncologist differ greatly. Only a thorough understanding of the nature of the biologic process as well as the capabilities and limitations of each treatment modality will allow selection of the most appropriate therapy for any individual patient.
- Megavoltage therapy. Despite the tremendous advance in technological equipment available to the radiation therapist, including computerized dosimeters, the proper treatment of lesions with minimal side effects requires an experienced and sophisticated therapist who understands both the nature of these tumors as well as the capabilities and limitations of his equipment.
- External Beam
- Gross removal of the primary tumor in its entirety
- Removal of all involved lymph nodes dependent on the histopathology of the tumor, the location of the tumor, the propensity for the tumor to metastasize, and general status of the patient
- Classical radical neck dissection-En bloc resection of lymphatics and soft tissue contained in superficial layer of deep cervical fascia to deep layer of deep cervical facia from the trapezius to the clavicle to the midline to mandible. Weakness of the shoulder because of the sacrifice of cranial nerve XI. The carotid artery and remaining cranial nerves are spared.
- Modified (conservation) neck dissection-resection of lymphatics and soft tissue within the limits defined above but with preservation of the sternocleidomastoid muscle, strap muscles, internal jugular vein, and cranial nerve XI. This is a technically difficult procedure and should be attempted only by experienced head and neck surgeons.
- Restoration of physiologic function and reconstruction of all significant physiological and cosmetic defects dependent on:
- Location of the tumor
- Extent of resection
- Reconstructive methods employed
- Patient's motivation and ability to adapt
Head and neck tumors frequently respond to chemotherapeutic agents. However, these drugs are used primarily for palliation or as adjuvant therapy in conjunction with surgery and radiation and have not replaced other modalities. Some drugs with proven activity in head and neck cancers:
- Treat underlying medical condition
- Supplemental nutrition
It often involves relearning such basic skills as swallowing and talking.
- Esophageal speech
- Electrical vibratory device
- Pharyngotracheal fistula
- Palatal and Orbital Resection Prostheses
- Allow swallowing and normal sounding speech
- Camouflage of large nasal and orbital defects
- Radical Neck Dissection-may need a physical therapist for shoulder weakness
- Monitor the patient's response to therapy
- To detect recurrence or second primary
- Every two months in the first year
- Every three months the second and third year
- At least every six months in the fourth and fifth years
- Yearly thereafter
The salivary glands are divided into the major glands (parotid, submandibular and sublingual) and minor glands (found in the submucosa of the nose, sinuses, mouth and upper aerodigestive tract). Tumors arise in both the major and minor glands, but are more frequent in the former. The most common site for a salivary tumor is the parotid gland and fortunately 70-80% are benign. Occurring less frequently than parotid lesions, submandibular and sublingual tumors are malignant in approximately 50% of cases. Minor salivary gland tumors are unusual and approximately 60% are malignant.
Types of Tumors
- Benign Mixed Tumor (Pleomorphic adenoma) - The most common tumor of the parotid gland
- Warthin's Tumor (papillary cystadenoma lymphomatosum) - Occurs most frequently in the "tail" of the parotid gland of white, middle aged males. Appear "hot" on Tc99 scan. Bilateral lesions not uncommon.
- Adenoid Cystic Carcinoma - Very lethal even when treated early. Although five-year survivals are quite good, 20 year survival is very poor-15% or less depending on site of origin. Most patients die of pulmonary metastases. This tumor also has a proclivity for perineural spread.
- Mucoepidermoid Carcinoma - Graded into high grade (very malignant and lethal) to low grade (very curable with surgery alone). The most common parotid tumor seen in childhood. Generally metastatic to lymph nodes.
- Acinic Cell Carcinoma - Low grade malignancy
- Squamous Cell Carcinoma - Very aggressive tumor. Must rule out metastasis from a skin lesion to parotid lymph nodes. Primary parotid lesions tend to metastasize to cervical lymph nodes.
- It is generally difficult to reliably differentiate benign from malignant lesions on the basis of history and physical examination. Facial paralysis and pain are almost exclusively associated with malignant lesions. A several year history of a slowly enlarging, lobulated mass is suggestive of a benign mixed tumor.
- Computerized axial tomography may be helpful, but is unreliable in accurately differentiating benign from malignant lesions.
- Thin needle aspiration is frequently accurate in diagnosing the lesions, but generally does not change the therapy which is surgical removal. Except for readily accessible, minor salivary gland lesions, open, incisional biopsy is to be condemned as this may lead to "seeding" or spread of the tumor, particularly the benign mixed tumor.
- Parotid Lesion - Complete excision of the tumor with a margin of surrounding normal salivary gland. Since the vast majority of lesions occur in the superficial lobe (lateral to the facial nerve) then the primary operation is a superficial parotidectomy with facial nerve dissection. This is potentially curative for all benign lesions and is generally the only surgery necessary for many malignant lesions. If a branch of the facial nerve is involved by a malignancy (particularly the adenoid cystic carcinoma) then that branch and perhaps all of the parotid gland and the facial nerve may need to be removed. A neck dissection is frequently indicated in squamous and high grade mucoepidermoid carcinomas.
- Submandibular and Sublingual Glands - Complete excisions of the gland and tumor. If a malignancy is discovered, then a neck dissection and perhaps excision of the floor of mouth may be indicated depending on the tumor type.
- Minor Salivary Glands - The operation depends on the location of the involved gland, but complete excision with a margin of normal tissue is essential. In the case of adenoidcystic carcinomas, surrounding nerves must be sampled for possible invasion and excised if involved.
Although not curative, most malignant salivary gland tumors respond to radiation therapy and it is usually incorporated into the treatment plan of the more ominous lesions (adenoid cystic carcinoma, adenocarcinoma, high grade mucoepidermoid carcinomas and squamous cell carcinomas). Radiation is used as the primary treatment for malignancies in patients who are poor surgical candidates. Radiation of benign lesions is not the accepted therapy in most circumstances in this country.