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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); 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, through the blood stream. Distant
metastates to the lung are most common.
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 all the time into the possible
causes.
Smoking, and heavy drinking of alcohol
(especially spirits) greatly increase the risk
of developing cancer of the larynx.
Cancer of the larynx 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 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 on
the size and location 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
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 larynx 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
performed, usually 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. 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.
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