Laryngeal cancer

Laryngeal cancer may also be called cancer of the larynx or laryngeal carcinoma. Most laryngeal cancers are squamous cell carcinomas, reflecting their origin from the squamous cells which form the majority of the laryngeal epithelium. Cancer can develop in any part of the larynx, but the cure rate is affected by the location of the tumor. For the purposes of tumour staging, the larynx is divided into three anatomical regions: the glottis (true vocal cords, anterior and posterior commissures); the supraglottis (epiglottis, arytenoids and aryepiglottic folds, and false cords); and the subglottis.

Most laryngeal cancers originate in the glottis. Supraglottic cancers are less common, and subglottic tumours are least frequent.

Laryngeal cancer may spread by direct extension to adjacent structures, by metastasis to regional cervical lymph nodes, or more distantly, through the blood stream. Distant metastates to the lung are most common.

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Causes

There is no single cause of laryngeal cancer. It is likely that several factors combine to cause it. Not all of these factors are known, but research is going on continually into possible causes.

Smoking and heavy drinking of alcohol (especially spirits) greatly increase the risk of developing laryngeal cancer.

Laryngeal cancer occurs mainly in middle-aged and older people, but it can occur in younger people who started smoking at an early age. It is more common in men than in women.

Risk factors

  Smoking is the most important risk factor for laryngeal cancer. Heavy chronic consumption of alcohol, particularly alcoholic spirits, is also significant. When combined, these two factors appear to have a synergistic effect. Some other quoted risk factors are likely, in part, to be related to prolonged alcohol and tobacco consumption. These include low socioeconomic status, male sex, and age greater than 55 years.

People with a previous history of head and neck cancer are known to be at higher risk (about 25%) of developing a second cancer of the head, neck, or lung. This is mainly because in a significant proportion of these patients, the aerodigestive tract and lung epithelium have been exposed chronically to the carcinogenic effects of alcohol and tobacco. In this situation, a field change effect may occur, where the epithelial tissues start to become diffusely dysplastic with a reduced threshold for malignant change. This risk may be reduced by quitting alcohol and tobacco.

Symptoms

The symptoms of laryngeal cancer depend on the size and location of the tumor. Symptoms may include the following:

• Hoarseness or other voice changes
• A lump in the neck
• A sore throat or feeling that something is stuck in the throat
• Persistent cough
• Stridor
• Bad breath
• Earache

Incidence

5 in 100,000 (12,500 new cases per year) in USA.^[1] The American Cancer Society estimates that 9,510 men and women (7,700 men and 1,810 women) will be diagnosed with and 3,740 men and women will die of laryngeal cancer in 2006.

Laryngeal cancer is listed as a "rare disease" by the Office of Rare Diseases (ORD) of the National Institutes of Health (NIH). This means that laryngeal cancer affects less than 200,000 people in the U.S.^[2]

Each year, about 2,200 people in the U.K. are diagnosed with laryngeal cancer.^[3]

Diagnosis

Diagnosis is made by the doctor on the basis of a careful medical history, physical examination, and special investigations which may include a chest x-ray, CT or MRI scans, and tissue biopsy. The examination of the larynx requires some expertise, which may require specialist referral.

The physical exam includes a systematic examination of the whole patient to assess general health and to look for signs of associated conditions and metastatic disease. The neck and supraclavicular fossa are palpated to feel for cervical adenopathy, other masses, and laryngeal crepitus. The oral cavity and oropharynx are examined under direct vision. The larynx may be examined by indirect laryngoscopy using a small angled mirror with a long handle (akin to a dentist's mirror) and a strong light. Indirect laryngoscopy can be highly effective, but requires skill and practice for consistent results. For this reason, many specialist clinics now use fibre-optic nasal endoscopy where a thin and flexible endoscope, inserted through the nostril, is used to clearly visualise the entire pharynx and larynx. Nasal endoscopy is a quick and easy procedure performed in clinic. Local anaesthetic spray may be used.

If there is a suspicion of cancer, biopsy is performed, usually under general anaesthetic. This provides definitive histological proof of cancer type and grade. If the lesion appears to be small and well localised, the surgeon may undertake excision biopsy, where an attempt is made to completely remove the tumour at the time of first biopsy. In this situation, the pathologist will not only be able to confirm the diagnosis, but can also comment on the completeness of excision, i.e., whether the tumour has been completely removed. A full endoscopic examination of the larynx, trachea, and esophagus is often performed at the time of biopsy.

For small glottic tumours further imaging may be unnecessary. In most cases, tumour staging is completed by scanning the head and neck region to accurately assess the local extent of the tumour and any pathologically enlarged cervical lymph nodes.

The final management plan will depend on the specific site, stage (tumour size, nodal spread, distant metastasis), and histological type. The overall health and wishes of the patient must also be taken into account.

Treatment

Specific treatment depends on the location, type, and stage of the tumour. Treatment may involve surgery, radiotherapy, or chemotherapy, alone or in combination. This is a specialised area which requires the coordinated expertise of dedicated ear, nose and throat (ENT) surgeons (otolaryngologists) and oncologists.

References