Epithelial carcinomas of the head and neck arise from the mucosal surfaces in the head and neck area and typically are squamous cell in origin. This category includes tumors of the paranasal sinuses, the oral cavity, and the nasopharynx, oropharynx, hypopharynx, and larynx. Tumors of the salivary glands differ from the more common carcinomas of the head and neck in etiology, histopathology, clinical presentation, and therapy. Thyroid malignancies are described in Chap. 341.
The number of new cases of head and neck cancers in the United States was 36,540 in 2010, accounting for about 3% of adult malignancies; 7880 people died from the disease. The worldwide incidence exceeds half a million cases annually. In North America and Europe, the tumors usually arise from the oral cavity, oropharynx, or larynx, whereas nasopharyngeal cancer is more commonly seen in the Mediterranean countries and in the Far East.
Alcohol and tobacco use are the most significant risk factors for head and neck cancer in the United States. Smokeless tobacco is an etiologic agent for oral cancers. Other potential carcinogens include marijuana and occupational exposures such as nickel refining, exposure to textile fibers, and woodworking.
Dietary factors may contribute. The incidence of head and neck cancer is higher in people with the lowest consumption of fruits and vegetables. Certain vitamins, including carotenoids, may be protective if included in a balanced diet. Supplements of retinoids such as cis-retinoic acid have not been shown to prevent head and neck cancers (or lung cancer) and may increase the risk in active smokers.
Some head and neck cancers have a viral etiology. Epstein-Barr virus (EBV) infection is frequently associated with nasopharyngeal cancer. Nasopharyngeal cancer occurs endemically in some countries of the Mediterranean and Far East, where EBV antibody titers can be measured to screen high-risk populations. Nasopharyngeal cancer has also been associated with consumption of salted fish.
In Western countries, the human papilloma virus (HPV) is associated with approximately 50% of tumors arising from the oropharynx, i.e., the tonsillar bed and base of tongue. Similar to cervical cancer, HPV 16 and 18 are the commonly associated viral subtypes. The incidence of oropharyngeal cancers is increasing in Western counties. Epidemiologically HPV-related oropharyngeal cancer occurs in a younger patient population and is associated with increased numbers of sexual partners and oral sexual practices.
No specific risk factors or environmental carcinogens have been identified for salivary gland tumors.
Squamous cell head and neck cancers can be divided into well-differentiated, moderately well-differentiated, and poorly differentiated categories. Poorly differentiated tumors have a worse prognosis than well-differentiated tumors. For nasopharyngeal cancers, the less common differentiated squamous cell carcinoma is distinguished from nonkeratinizing and undifferentiated carcinoma (lymphoepithelioma) that contains infiltrating lymphocytes and is commonly associated with EBV.
Salivary gland tumors can arise from the major (parotid, submandibular, sublingual) or minor salivary glands (located in the submucosa of the upper aerodigestive tract). Most parotid tumors are benign, but half of submandibular and sublingual gland tumors and most minor salivary gland tumors are malignant. Malignant tumors include mucoepidermoid and adenoid cystic carcinomas and adenocarcinomas.
The mucosal surface of the entire pharynx is exposed to alcohol- and tobacco-related carcinogens and is at risk for the development of a premalignant or malignant lesion. Erythroplakia (a red patch) or leukoplakia (a white patch) can be histopathologically hyperplasia, dysplasia, carcinoma in situ, or carcinoma. However, most head and neck cancers do not present with a history of premalignant lesions. Multiple synchronous or metachronous cancers can also be observed. In fact, over time patients with early-stage head and neck cancer are at greater risk of dying from a second malignancy than from a recurrence of the primary disease.
Second head and neck malignancies are usually not therapy-induced; they reflect the exposure of the upper aerodigestive mucosa to the same carcinogens that caused the first cancer. These second primaries develop in the head and neck area, the lung, or the esophagus. Rarely, patients can develop a radiation therapy–induced sarcoma after having undergone prior radiotherapy for a head and neck cancer.
The molecular carcinogenesis of head and neck cancer is a developing story. Activation of oncogenes and inactivation of tumor suppressor genes (frequently of p53) have been described. Overexpression of the epidermal growth factor receptor (EGFR) is common and of prognostic importance.
Resected tumor specimens with histopathologically negative margins ("complete resection") can have residual tumor cells with persistent p53 mutations at the margins. Thus, a tumor-specific p53 mutation can be detected in some phenotypically "normal" surgical margins, indicating residual disease. Patients with such submicroscopic marginal involvement may have a worse prognosis than patients with truly negative margins.
Most head and neck cancers occur in patients older than age 50 years. HPV-related malignancies are frequently diagnosed in patients in their 40s while EBV-related nasopharyngeal cancer can occur in all ages, including teenagers. The manifestations vary according to the stage and primary site of the tumor. Patients with nonspecific signs and symptoms in the head and neck area should be evaluated with a thorough otolaryngologic exam, particularly if symptoms persist longer than 2–4 weeks.
Cancer of the nasopharynx typically does not cause early symptoms. However, on occasion it may cause unilateral serous otitis media due to obstruction of the eustachian tube, unilateral or bilateral nasal obstruction, or epistaxis. Advanced nasopharyngeal carcinoma causes neuropathies of the cranial nerves due to skull base involvement.
Carcinomas of the oral cavity present as nonhealing ulcers, changes in the fit of dentures, or painful lesions. Tumors of the tongue base or oropharynx can cause decreased tongue mobility and alterations in speech. Cancers of the oropharynx or hypopharynx rarely cause early symptoms, but they may cause sore throat and/or otalgia.
Hoarseness may be an early symptom of laryngeal ...