Laryngeal cancer

ALSO KNOWN AS: Cancer of the larynx, voice box cancer

RELATED CONDITIONS: Cancer of the lymph nodes, throat cancer, lung cancer, bone cancer, liver cancer

DEFINITION: Laryngeal cancer is a cancer of the larynx, or voice box. The larynx is between the pharynx, the passage that connects the back of the mouth and nose to the esophagus and the trachea. It is a muscular passage through which food passes from the back of the mouth toward the stomach. Laryngeal cancer is a type of head and neck cancer.

The larynx has three divisions. The upper portion is called the supraglottic larynx and contains the false vocal cords, the epiglottis or small flap that keeps food from entering the lungs, and other structures high in the throat toward the base of the tongue. The glottis is below the supraglottic larynx and contains the true vocal cords. The subglottis lies below the glottis and continues down the throat to the first cartilage ring surrounding the trachea.

Risk factors: The major risk factors for laryngeal cancer are tobacco use and moderate or heavy alcohol consumption. This cancer is four times more common in men, especially those over the age of sixty, than in women. In the late 1990s, ten men were afflicted by this disease for every woman who suffered from it. However, an increase in the number of women with the disease later occurred, correlating with an increase in the number of women smokers. Men are around five times as likely to have cancers of the larynx and hypopharynx.

A link has been detected between laryngeal cancer and long-term occupational exposure to particular carcinogens, notably nickel, mustard gas, and fumes from sulfuric acid. Individuals who work in the metal, petroleum, construction, and textile industries are at an increased risk of exposure to such chemicals. Some studies suggest a link between exposure to asbestos and laryngeal cancer. Additionally, individuals with a family history of laryngeal cancer are at an increased risk, mainly if the family member is under sixty at diagnosis.

The presence of some conditions, such as gastroesophageal reflux disease (GERD) or Plummer-Vinson syndrome, and inherited conditions, like Fanconi anemia and congenital dyskeratosis.

Etiology and the disease process: Laryngeal cancer can form in any part of the larynx, although 60 percent of cases start in the glottis. About 35 percent begin in the supraglottic area. A small number of cases develop in the subglottis. Almost all cancers of the larynx start in the squamous cells that line its inner walls, and these cancers are known as squamous cell carcinomas. The cancer can spread (metastasize) to the lymph nodes in the neck, the back of the tongue, and other parts of the throat and neck. It also can reach the lungs and liver.

Incidence: Laryngeal cancer is a relatively rare form of cancer, accounting for about 1.1 percent of all cancers worldwide but 30 to 40 percent of head and neck malignancies. The American Cancer Society estimates there are more than 12,000 new cases of laryngeal cancer and over 3,000 deaths due to the disease each year. There has been a notable overall decrease in laryngeal cancer since the 1990s as tobacco smoking has become less prevalent.

In their lifetime, men have a one in two hundred chance of developing laryngeal cancer, and women have a one in eight hundred forty chance.

Symptoms: Cancer of the supraglottic larynx may result in a persistent sore throat. Sometimes, swallowing is complex, and choking is frequent. Changes in the voice or hoarseness may be detected. Some people suffering from the disease suffer from pain in the ears. If the cancer develops in the glottis, some of these symptoms are present, including significant hoarseness caused by tumors on the vocal cords. Cancer in the subglottis, which involves the true vocal cords and may continue to the first cartilaginous ring surrounding the trachea, is quite rare, although some cases have been reported. In subglottic laryngeal cancer, patients may experience shortness of breath besides hoarseness. Their breathing may be labored and noisy.

Symptoms of the disease that cannot be ignored and require immediate medical attention are hoarseness that persists for two weeks or longer, a lingering sore throat, difficulty in swallowing accompanied by frequent choking, swelling in the neck, and, sometimes, pain in the ears.

Screening and diagnosis: When a small tumor grows in the glottis, it can cause pronounced and prolonged hoarseness, which often will lead patients to see their physicians while the cancer is still at in an early stage and is most likely to be cured. However, symptoms often develop gradually and may be ignored until they become quite pronounced.

When symptoms appear, a laryngoscopy is indicated. This procedure can be performed by using a mirror and light to examine the area or by using an endoscope inserted into the affected area for a more extensive examination. Usually, tissue is taken from the vocal cord and biopsied to determine whether it is cancerous. Such techniques work well if the area involved is the supraglottis or glottis. If the subglottis is involved, however, endoscopic examination is essential, and it is only partially reliable because the vocal cords often obscure the area that requires examination.

Other tests may include computed tomography (CT), functional magnetic resonance imaging (fMRI), and a barium swallow.

The most commonly used staging system for laryngeal cancer is the American Joint Committee on Cancer TNM, which considers the size of the tumor and whether it has spread to the lymph nodes or distant parts of the body. The stages range from Stage 0 (carcinoma in situ) to Stage IV, with the spread of the cancer to distant organs. Stage definitions differ depending on whether the cancer is in the supraglottis, glottis, or subglottis.

Treatment and therapy: If a small cancerous growth is discovered early, it is usually treated with radiation, although in some cases, surgery is indicated. Surgery is avoided if possible because it can damage the vocal cords and lead to speaking problems. Advances in surgical techniques, like transoral robotic surgery (TORS) and transoral video laryngoscopic surgery (TOVS), are continually explored as alternatives to highly invasive, life-altering surgeries.

Biopsies must be done on any tissue that is removed. If the biopsy indicates a malignancy, further investigation is required to determine whether the malignancy has spread to such sites as lymph nodes, throat, lungs, throat, tongue, liver, and bones. Advanced cancers that produce large tumors may require a laryngectomy, the surgical removal of the voice box. This treatment is usually a last resort treatment because it robs the patient of the ability to speak normally. However, extensive speech therapy can teach people to produce speech through an artificial larynx or esophageal speech. In Stage III and IV laryngeal cancer, surgery is usually followed by both radiation and chemotherapy. In some cases, immunotherapy, such as pembrolizumab or nivolumab, is used alone or with chemotherapy. EGFR inhibitors like Cetuximab (Erbitux) may be effective in treating laryngeal cancer at all stages.

Cancers that develop below the vocal cords are particularly problematic because the vocal cords can prevent these cancers from being seen. Also, subglottal tumors and their lesions do not produce symptoms early in the disease. By the time symptoms occur, the cancer may be well advanced.

Prognosis, prevention, and outcomes: Laryngeal cancers are often curable if detected early and treated aggressively. The five-year survival rate for localized laryngeal cancer is 60 to 80 percent. In contrast, the five-year survival rate of those with regional laryngeal cancer (with spread to regional lymph nodes) is 30 to 40 percent, and those with distant laryngeal cancer is 19 percent.

Prevention offers the best hope for controlling laryngeal cancers. The two most identifiable causes of such cancers are smoking and heavy drinking. Although abstinence from tobacco products and alcohol cannot guarantee that someone will not develop laryngeal cancer, it is clear that most of those suffering from this disease have abused tobacco, alcohol, or both. Once symptoms appear, those who smoke or drink should stop doing so immediately.

Bibliography

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