Throat cancer

ALSO KNOWN AS: Oropharyngeal cancer, laryngeal cancer, pharyngeal cancer, nasopharyngeal cancer

RELATED CONDITIONS: Thyroid cancer, vocal cord cancer, cancer of the glottis, adenoid cystic carcinoma, mucoepidermoid carcinoma, polymorphous low-grade adenocarcinoma

DEFINITION: Throat cancer is a malignant tumor in the tissues of the pharynx (part of the alimentary canal from behind the nose to the top of the esophagus) or in the larynx (voice box). The pharynx is divided into the nasopharynx (upper part behind the nose), oropharynx (middle part including the soft palate, base of tongue, and tonsils), and hypopharynx (lower part).

Risk factors: Studies have found that as many as 90 percent of people with head and neck cancers, particularly of the oropharynx, hypopharynx, and larynx, have a history of smoking or chewing tobacco, and as many as 80 percent have a history of drinking alcohol. Risk increases with the frequency, duration, and number of “pack-years” of cigarette smoking, independent of alcohol consumption. (One pack-year is defined as equivalent to smoking one pack, or twenty cigarettes, per day for one year.) One study indicated that smoking or chewing tobacco in conjunction with excess drinking of alcohol increases the risk beyond that for those who use either tobacco or alcohol alone. In a study among those who never smoked, only those with excessive amounts of alcohol consumption (three or more drinks per day) were at increased risk of head and neck cancers.

Other factors vary by tumor site and include Chinese ancestry, consumption of preserved and salted foods, wood dust exposure, and infection with the Epstein-Barr virus for nasopharyngeal cancer; poor oral hygiene; a diet low in fruits and vegetables, chewing betel quid, and infection with the human papillomavirus (HPV) for oropharyngeal cancer; Plummer-Vinson syndrome, a disorder characterized by severe anemia and trouble swallowing, for hypopharyngeal cancer; and asbestos exposure for laryngeal cancer. Individuals of East Asian descent who drink alcohol and possess a genetic mutation that prevents the effective elimination of acetaldehyde, a carcinogen created by the metabolism of alcohol, are at greater risk for oropharyngeal cancer.

Etiology and the disease process: Most throat cancers begin in squamous cells lining mucosal surfaces in the throat. Squamous cell cancers grow aggressively. They begin as carcinomas in situ, abnormal cells lining the cells in the epithelium before they progress to invasive squamous cell cancers. Salivary gland tumors can develop in the mucosal lining of the oropharynx and oral cavity.

What makes squamous cells become cancerous is unknown. Still, it is believed that tobacco and alcohol use damage the deoxyribonucleic acid (DNA) in the cells of the mouth and throat, causing changes that lead to cancer.

Incidence: Each year, around 58,000 individuals are diagnosed with oral cavity or oropharyngeal cancer. Cancers of the throat occur more often in men than in women, with men making up approximately 80 percent of those with hypopharyngeal cancer and 70 percent of those with nasopharyngeal cancer. Around one in fifty-nine men and one in 139 women are diagnosed with oral or oropharyngeal cancer in their lifetime. The incidence of head and neck cancers has generally declined since the 1980s, attributable in part to a drop in the number of people smoking cigarettes. The average age at diagnosis is sixty-four, but about 30 percent of cases occur in individuals under fifty-five.

Symptoms: Symptoms of throat cancer may be mild or absent but may include a lump or sore that does not heal or becomes larger, sore throat, trouble swallowing, and a change in voice, such as hoarseness. Patients with cancer of the oropharynx or hypopharynx may experience ear pain, and those with cancer of the nasopharynx may have ear pain and difficulty hearing, headaches, and difficulty breathing or talking. Symptoms of cancer of the larynx may include sore throat, hoarseness, ear pain, or a lump in the neck.

Screening and diagnosis: There are no routine screening tests for throat cancer for asymptomatic patients. If throat cancer is suspected, the physician will take a complete medical history for risk factors and perform a physical exam. During the physical exam, the physician will palpate for lumps in the throat to rule out other conditions related to the symptoms, look for signs of metastasis, and determine the patient’s overall health. Then, the physician will most likely perform an endoscopy to view areas that are not visible during a physical exam and to look for lesions. (A laryngoscope examines the larynx; a nasopharyngoscope examines the nasal cavity and nasopharynx.) During this procedure, the physician will excise tissue for examination. Depending on the tumor's location, the biopsy can be one of three typesan exfoliative biopsy, incisional biopsy, or fine needle aspiration biopsy (commonly done to stage oropharyngeal cancer). The physician may recommend a panendoscopy, a diagnostic procedure done under general anesthesia during surgery to thoroughly examine the nose, throat, voice box, esophagus, and bronchi to look for areas of lesions and obtain a biopsy.

If cancer is present, it is staged from Stage 0, localized cancer, to Stage IV, metastasized cancer. Staging depends on the pathology results, clinical data such as endoscopy results, physical examination findings, and imaging studies results. Imaging studies may include an X-ray to determine if there is cancer in the lungs; computed tomography (CT) scans for a cross-sectional picture of the size, location, shape, and position of the tumor; magnetic resonance imaging (MRI); positron emission tomography (PET) to see if cancer has spread to nearby lymph nodes; and a barium swallow, a series of X-rays to determine if cancer has spread to the esophagus in the digestive tract and to see if it affects swallowing.

Treatment and therapy: If cancer is present, the physician will discuss treatment options, considering the patient’s overall health, prognosis, staging, psychosocial supports, treatment side effects, and the impact of cancer and treatment on functions such as swallowing, talking, and chewing. The patient’s medical team may include otorhinolaryngologists, oral surgeons, pathologists, plastic surgeons, prosthodontists, and radiation and medical oncologists. Other allied health professionals may be involved, such as dieticians, speech pathologists, physical therapists, and social workers.

Surgery and radiation therapies are commonly used for treating throat cancers, mainly when the tumor is small and can be destroyed before spreading. Radiation therapy may follow surgery if it fails to remove all the cancer, or radiation may be used before surgery to preserve the voice. Individuals receiving radiation therapy may experience side effects, including nausea, irritation, and sores in the mouth, decreased appetite, earaches, and stiffness in the jaw.

If a larger tumor is involved or if the cancer has spread, a combination of radiation and chemotherapy is often successful and can preserve the voice box. Rarely will a partial laryngectomy be recommended, and only in cases in which the larynx and primary tumor must be removed. Palliative care is needed for individuals whose primary throat cancer has spread to other organs or distant parts of the body and cannot be treated.

Prognosis, prevention, and outcomes: The five-year survival rates for throat cancers vary based on the location and the stage of the cancer at the time it was found. The five-year survival rate for stage 1 laryngeal cancer is around 90 percent, stage 2 is around 70 percent, stage 3 is around 60 percent, and stage 4 is just over 30 percent.

The five-year survival rate is 61 to 70 percent for stage I hypopharyngeal cancer and 70 to 80 percent for stage I nasopharyngeal cancer. However, these rates drop when these cancers are detected after metastasis. According to the American Cancer Society (ACS), the relative five-year survival rate is 67 percent for cancers of the oropharynx and tonsils.

Rehabilitation is often a critical component in caring for throat cancer patients. Many patients need therapy for assistance in speaking and swallowing following treatment. Patients may also need dietary counseling. Those who receive a laryngectomy will have a stoma—a surgical opening in the throat. They must learn how to care for it and to speak again if the stoma is permanent.

Follow-up care for those treated for throat cancer is essential to ensure the cancer does not recur. Individuals with a prior diagnosis of throat cancer are at the highest risk of recurrence of the cancer within two to three years of initial diagnosis. During follow-up visits, the physician will perform a physical exam and sometimes order X-rays, blood tests, and imaging studies. Regular dental exams may be necessary as well. If patients receive radiation therapy, the physician may monitor the functioning of the thyroid and pituitary glands. Physicians also urge patients to stop drinking alcohol and smoking, as alcohol and tobacco compromise treatment and increase the risk that a second cancer will develop.

Bibliography

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