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Cancer of the larynx also may be called laryngeal cancer or laryngeal carcinoma. Cancer can develop in any part of the larynx. Most laryngeal cancers are squamous cell carcinomas, reflecting their origin from the squamous cells which form the majority of the laryngeal epithelium. 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); the subglottis.
Most laryngeal cancers originate in the glottis. Supraglottic cancers are less common, and subglottic tumours are least frequent.
Laryngeal cancer may spread, either by direct extension to adjacent structures, by metastasis to regional cervical lymph nodes or more distantly, to the lung in particular.
Risk Factors
In the Western world, 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 much higher risk (about 25%) of developing a second cancer of the head and neck, or lung cancer (about 10%.)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 to 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 cancer of the larynx depend mainly on the size of the tumor and where it is in the larynx. 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
Needless to say, these symptoms are not specific for cancer.
Diagnosis
Diagnosis is made by the doctor on the basis of a careful medical history, physical examination, and special investigations which may include Chest X-Ray, CT or MRI scans, and tissue biopsy. The examination of the throat requires some expertise, which may require specialist referral.
The physical exam includes a systematic examination of the whole patient to assess general health, 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 usually performed under general anesthetic. 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.
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.
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