喉癌-Cancer of the Larynx

The larynx is the top part of the trachea (windpipe). It is about 5 cm long and is sometimes called the 'voice-box'. You can see and feel the front part of the larynx as the 'Adam's apple' on the front of the neck, just below the chin.

The larynx contains the vocal cords. These are 'V' shaped ridges of muscle tissue on the inside lining of the larynx. They vibrate when air passes between them to produce speech.

When you breathe in, air passes into the larynx and down the trachea towards the lungs. When you swallow, the larynx moves upwards slightly and a flap of cartilage tissue at the back of the tongue called the epiglottis closes over the entrance to the larynx. This ensures that food or drink go down the oesophagus (gullet) and not down the trachea.

What is cancer?

Cancer is a disease of the cells in the body. The body is made up from millions of tiny cells. There are many different types of cell in the body, and there are many different types of cancer which arise from different types of cell. What all types of cancer have in common is that the cancer cells are abnormal and multiply 'out of control'.

A malignant tumour is a 'lump' or 'growth' of tissue made up from cancer cells which continue to multiply. As they grow, malignant tumours invade into nearby tissues and organs which can cause damage.

Malignant tumours may also spread to other parts of the body. This happens if some cells break off from the first (primary) tumour and are carried in the bloodstream or lymph channels to other parts of the body. These small groups of cells may then multiply to form 'secondary' tumours (metastases) in one or more parts of the body. These secondary tumours may then grow, invade and damage nearby tissues, and spread again.

Some cancers are more serious than others, some are more easily treated than others (particularly if diagnosed at an early stage), some have a better outlook (prognosis) than others.

So, cancer is not just one condition. In each case it is important to know exactly what type of cancer has developed, how large it has become, and whether it has spread. This will enable you to get reliable information on treatment options and outlook. See separate leaflet called 'What are Cancer and Tumours' for further details about cancer in general.

What is cancer of the larynx?

Cancer of the larynx is sometimes called layngeal cancer. Some people also call it 'throat cancer'. However, the throat includes the larynx and other nearby structures. Cancer of the larynx is just one type of cancer that can occur in the throat. Cancer of the larynx is uncommon in the UK with around 2000-2500 cases developing each year. It is four times more common in men than women. There are different types of cancer of the larynx.

• Squamous cell carcinoma of the larynx occurs in more than 9 in 10 cases. This type arises from cells which are on the inside lining of the larynx.
• Other types. There are some rare types of cancer which arise from other types of cells within the larynx. For example, adenocarcinoma of the larynx arises from cells in the tiny glands in the wall of the larynx that make mucus. There are some other very rare types.

The rest of this leaflet is about squamous cell carcinoma of the larynx.

What causes cancer of the larynx?

A cancerous tumour starts from one abnormal cell. The exact reason why a cell becomes cancerous is unclear. It is thought that something damages or alters certain genes in the cell. This makes the cell abnormal and multiply 'out of control'. (See separate leaflet called 'What Causes Cancer' for more details.)

Some people develop cancer of the larynx for no apparent reason. However, certain 'risk factors' increase the chance that cancer of the larynx may develop. These include:

• Ageing. It is more common in older people. Most cases are in people over the age of 50.
• Smoking. The damaging smoke passes the larynx to get to the lungs. Cancer of the larynx is just one cancer which has a much higher incidence in smokers than non smokers.
• Drinking a lot of alcohol, particularly if you are also a smoker.
• A poor diet is possibly a risk factor, especially a diet lacking certain vitamins and minerals.
• Long-term exposure to certain chemicals, fumes or pollutants (chemical carcinogens) may 'irritate' the larynx if you breathe them in and may increase the risk.
• Long-standing acid reflux from the stomach (gastro-oesophageal reflux disease or GORD). This condition is common and often causes inflammation at the lower end of the oesophagus. In more severe cases, acid may reflux high up to the level of the larynx and may be a possible risk factor.

What are the symptoms of cancer of the larynx?

• A hoarse voice is often the first symptom to develop. This is because most cancers of the larynx first start on, or close by, a vocal cord. The problem is, a hoarse voice is a common symptom of laryngitis (a viral infection of the larynx). Most people with hoarseness do not have cancer. However, laryngitis usually clears within a week or so. Therefore, see a doctor if you develop a hoarse voice which does not go within 2-4 weeks.
• Other symptoms that may occur as the tumour grows in the larynx include: a lump in the throat, pain in the throat when swallowing, difficulty with breathing. These symptoms may occur before a hoarse voice develops if the tumour does not start next to the vocal cords.
• If the cancer spreads to local lymph nodes (lymph glands) then the nearby glands in the neck will swell.
• If the cancer spreads to other parts of the body, various other symptoms can develop.

All the symptoms can be due to other conditions, so tests are needed to confirm the diagnosis.

How is cancer of the larynx diagnosed and assessed?

Initial assessment
If a doctor suspects that you may have cancer of the larynx, he or she will refer you to a specialist in ENT (ear nose and throat). The specialist will examine the inside of your throat by using a small mirror and light. He or she may also use a thin, flexible, telescope (a nasendoscope). This is passed into your nose and down the back of your throat. The nasendoscope contains fibre optic channels which allows light to shine down so the doctor can see inside. (The throat is usually sprayed with a local anaesthetic before using a nasendoscope so the procedure is not too uncomfortable.)

To confirm the diagnosis
If anything suspicious is seen by the examination or with the nasendoscope you will usually need a biopsy. A biopsy is when a small sample of tissue is removed from a part of the body. The sample is then looked at under the microscope to look for abnormal cells. A biopsy of a tumour in a larynx is normally done under general anaesthetic and so will need a short hospital stay. The biopsy sample is obtained by a thin, flexible grabbing instrument which is passed through your nose into the larynx whilst you are under anaesthetic. The same instrument has a light source similar to a nasendoscope and so the specialist will also examine the trachea and oesophagus to see the extent of any tumour. 醫(yī)學(xué)全.在線提供

Assessing the extent and spread (staging)
In addition to the above tests, if you are confirmed to have cancer of the larynx then further tests may be done. For example, biopsy samples may be taken from the nearby lymph glands by using a fine needle. This helps to assess if any cancer cells have spread to the lymph glands. Other tests may be arranged to see if the cancer has spread to other parts of the body. For example, a CT scan, an MRI scan, or other tests. (There are separate leaflets which describe each of these tests in more detail.)

This assessment is called 'staging' of the cancer. The aim of staging is to find out:

• How much the tumour in the larynx has grown.
• Whether the cancer has spread to local lymph nodes.
• Whether the cancer has spread to other areas of the body (metastasised).

Grade of the cancer
The biopsy samples are looked at under the microscope to asses the cancer cells. By looking at certain features of the cells the cancer can be 'graded'. The common grading system used for cancer of the larynx is:

• Grade 1 (low grade). The cells look reasonably similar to normal cells in the larynx. The cancer cells are said to be 'well differentiated'. The cancer cells tend grow and multiply quite slowly and are not so 'aggressive'.
• Grade 2 (intermediate grade).
• Grade 3 (high grade). The cells look very abnormal and are said to be 'poorly differentiated'. The cancer cells tend to grow and multiply quite quickly and are more 'aggressive'.

By finding out the stage and grade of the cancer it helps doctors to advise on the best treatment options. It also gives a reasonable indication of outlook (prognosis). However, for cancer of the larynx, it may not be possible to give an accurate staging until after an operation to remove the tumour.

See separate leaflet called 'Cancer Staging and Grading' for more details.

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