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Eye Cancer

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Posted by on Monday, October 18, 2010, 6:28
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Ocular Melanoma:

Ocular melanoma is melanoma of the eye. Melanoma is a cancer that develops from cells called melanocytes. Melanocytes produce the dark-coloured pigment melanin, which is responsible for the colour of our skin. These cells are found in many places in our body, including the skin, hair, and lining of the internal organs, including the eye.

Eye Cancer
Eye Cancer

Most melanomas begin to grow in the skin, but it is also possible for a melanoma to begin in other parts of the body, such as the eye.

Diagram showing the structure of the eye

Within the eye itself, melanoma can develop in one of several places. Uveal melanoma is the most common type of ocular melanoma. This means it occurs along the uveal tract of the eye (the darker ring on the diagram), which includes the choroid, ciliary body and iris.

The choroid is part of the lining of the eyeball. It is dark-coloured (pigmented) to prevent light being reflected around the inside of the eye. The ciliary body extends from the choroid and focuses the eye by changing the shape of the lens. The iris is the clearly visible coloured disc at the front of the eye, which controls the amount of light entering the eye. All these structures are coloured with melanin.

Melanoma can also occur in the thin lining over the white part of the eye (the conjunctiva) or on the eyelid, but this is very rare. This is known as conjunctival melanoma .

Ocular melanoma is the most common type of cancer to affect the eye, although generally it is still quite rare. Approximately 500 new cases of ocular melanoma are diagnosed in the UK each year. The incidence of ocular melanoma increases with age, and most cases are diagnosed in people in their 50s.
This is a rare type of tumour and, as for many other forms of cancer, the exact cause is unknown. It is known that exposure to ultraviolet (UV) rays (either from the sun or sunbeds) increases the risk of developing melanoma of the skin. People whose skin burns easily are most at risk – people with fair skin, fair or red hair and blue eyes. However, it is not yet known whether or not there is any link between UV ray exposure and the development of melanoma of the eye.

Ocular melanoma may be more common in people who have atypical mole syndrome, which is also called dysplastic naevus syndrome. People with this condition have a greater risk of developing a melanoma of the skin, and often have over 100 moles on their body, some of which are abnormal in size and shape.
Signs and symptoms

Symptoms include blurred vision, flashing lights and shadows. Often, no symptoms are noticed and an ocular melanoma may be diagnosed by an optician during a routine sight test.

All of these symptoms are common to other conditions of the eye, but it’s usually possible for an eye specialist (ophthalmologist) to diagnose these tumours quite simply and painlessly. Occasionally, a small sample of tissue needs to be taken and examined (biopsy), to confirm a diagnosis.
How it is diagnosed

A number of tests may be done to diagnose ocular melanoma, including:

Ophthalmoscopy A small hand-held lens (ophthalmoscope) is used to look at the inside of the eye.

Ultrasound scan A small device which produces sound waves is rubbed over the skin around the eye area. The echoes are then converted into a picture by a computer.

Colour fundus photography Photographs of the back of your eye (fundus) are taken, and can help to show what the tumour looks like before and after treatment. For the test, your pupil will be dilated using eye drops, and a special camera will be used to take a picture of the fundus.

Biopsy A small sample of tissue may be taken from the suspicious area and examined under a microscope. However, this is not necessary for most ocular melanomas, because they have a distinctive appearance and can usually be recognised easily from x-rays and scans.

Other tests, which are used less frequently, include:

Fluorescein angiography A special dye called flourescein is injected into a vein in the arm. In a few seconds the dye travels to the blood vessels inside the eye. A camera with special filters that highlight the dye is used to photograph the flourescein as it circulates through the blood vessels in the retina and choroid.

CT (computerised tomography) scan A CT scan takes a series of x-rays which build up a three-dimensional picture of the inside of the body. The scan is painless but takes 10-15 minutes. CT scans use a small amount of radiation, which will be very unlikely to harm you and will not harm anyone you come into contact with. You will be asked to not eat or drink for at least foyr hours before the scan.

You may be given a drink or injection of a dye which allows particular areas to be seen more clearly.  This may make you feel hot all over for a few minutes. If you are allergic to iodine or have asthma you could have a more seriousreaction to the injection, so it is important to let your doctor know beforehand.

MRI (magnetic resonance imaging) scan This test is similar to a CT scan but uses magnetism instead of x-rays to build up a detailed picture of areas of your body. Before the scan you may be asked to complete and sign a checklist. This is to make sure that it’s safe for you to have an MRI scan (because the scanner is a powerful magnet).

Before having the scan, you’ll be asked to remove any metal belongings including jewellery. Some people are given an injection of dye into a vein in the arm, which doesn’t usually cause discomfort. This is called a contrast medium and can help the images from the scan to show up more clearly. During the test you will be asked to lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It is painless but can be slightly uncomfortable, and some people feel a bit claustrophobic during the scan. It’s also noisy, but you’ll be given earplugs or headphones.

A number of different treatments are used for ocular melanoma, depending on the size, cell type and position of the tumour, and other factors such as your general health, age and level of vision in both eyes. The aim of the treatment is to destroy the cancer cells, stop the cancer coming back, and to save as much of your vision as possible.

Some of the treatments for melanoma of the eye are very specialised, and only available at a few hospitals in the UK, so you may have to travel to one of these centres for your treatment.

This type of treatment uses high-energy rays to destroy the cancer cells, while doing as little harm as possible to normal cells. Radiotherapy| may be given either from outside the body (external radiotherapy) or from within (internal radiotherapy).

Radiotherapy may be the only treatment, or it may be given after surgery. Recent developments in radiotherapy have made it possible to preserve sight in the eye, either completely or partly.

External radiotherapy In external radiotherapy a beam of radiation is directed to the area of the tumour. The treatment is normally given as small doses called fractions over a few days. Different types of radiotherapy machines can be used. One, called a cyclotron, is specifically used to treat eye tumours. It directs a proton radiation beam precisely at the affected area, causing as little radiation exposure as possible to the surrounding healthy eye tissue. Before the treatment, a minor operation is carried out to attach small metal tags to various parts of the eye. The tags act as markers for the radiation beam.

Internal radiotherapy This treatment is given by placing a radioactive source called a plaque close to the tumour. This normally involves a stay in hospital of up to a week. Using a local anaesthetic to numb the eye and sedation to make you feel relaxed, the radioactive plaque is placed close to the tumour in the eye. A general anaesthetic can be used if preferred. Another operation is carried out to remove it when the treatment is finished.

Certain precautions need to be taken while the plaque is in your eye. You will need to stay in one room and each member of staff and your visitors will only be allowed in for a short time each day. This is to reduce any unnecessary exposure to radiation. Once the radioactive source is removed, no precautions will be necessary, as the radiation will no longer be present.
Transpupillary thermotherapy (TTT)

This can be used to treat very small ocular melanomas, or as an additional treatment after radiotherapy. The tumour is heated with a special type of laser beam. Cancer cells are more susceptible to heat than normal cells and so will be destroyed. Several treatments are normally needed. This will be done using a local anaesthetic and sedation to relax you.

This may involve removing just the tumour, a small part of the eye or sometimes the whole eye. The type of operation you have depends on the size and position of the tumour.

Your surgeon will try to preserve your eye. However, if the cancer is growing rapidly, or is large or painful, removal of the eyeball may be the most appropriate treatment for you. This is called enucleation . Your surgeon will only recommend this operation if it’s absolutely necessary.

For many people this suggestion can be quite shocking and a lot of discussion may be needed with the doctors involved before the decision to go ahead is taken. You can have an artificial eye (prosthesis) made that matches your remaining eye. An implant can be inserted which makes the artificial eye move realistically.

The thought of having any type of surgery| to your eye can be frightening and you may have worries about how your sight will be affected. You can talk over your concerns with your eye surgeon or specialist nurse; they will answer any questions before you have your operation.

Eye surgery will be carried out by a specialist surgeon and you will either be given a general anaesthetic or a local anaesthetic and sedation.
Conjunctival melanoma

Melanoma affecting the thin lining over the white part of the eye (the conjunctiva) is rare. Some conjunctival melanomas may be due to sun exposure, and in this way they are like those of the skin which are more common in people with fair colouring and pale eyes who burn more easily in the sun.

However, most conjunctival melanomas develop from a very rare condition called primary acquired melanosis (PAM), which causes brown/dark patches (pigmentation) on the conjunctiva. Sometimes the melanoma will develop from an existing freckle or mole on the conjunctiva. Any new pigmentations, or changes to an existing area, should be checked with your doctor.

A conjunctival melanoma is diagnosed by taking a small sample of cells from the pigmented area (a biopsy). If a melanoma is diagnosed, the abnormal area (and a margin of surrounding healthy cells) will be removed during a small operation. The surgery may be followed by treatment called cryotherapy. This involves freezing the area to kill any melanoma cells that may have been left behind after surgery. Sometimes, radiotherapy may be used instead of cryotherapy. This involves brief daily treatments over a week or so, using a small radioactive disc shaped like a contact lens. Occasionally eye drops containing chemotherapy drugs may be used. This is known as topical chemotherapy.

If the melanoma is quite large, it may sometimes be necessary to completely remove the conjunctiva as well as the eyeball. This is a rare operation and is called an orbital exenteration. After this type of surgery you will need a facial prosthesis (false part), which covers the eye socket and contains false lids, lashes and an artificial eye. The eye will not be able to move or open or close. The prosthesis can be mounted on to a pair of glasses, or fixed to your face with a special glue. Alternatively, studs may be fixed into the bone around the eye socket, although this is rare.

The thought of this operation can be very distressing and you may need to spend time talking it through with your doctor or specialist nurse, who can answer any questions you may have. Ongoing support will be available to help you cope at this difficult time – from doctors, counsellors and patient support groups.
Research trials

Research into treatments for ocular melanoma is ongoing and advances are being made. Cancer doctors use clinical trials to assess new treatments. Before any trial is allowed to take place an ethics committee must have approved it and agreed that the trial is in the interest of patients.

You may be asked to take part in a clinical trial| . Your doctor must discuss the treatment with you so that you have a full understanding of the trial and what it involves. You may decide not to take part, or to withdraw from a trial at any stage. You will then receive the best standard treatment available.
Follow up

After your treatment is completed, you will have regular check-ups and possibly scans or x-rays. These will probably continue for several years. If you have any problems, or notice any new symptoms between these times, let your doctor know as soon as possible.

Ocular melanoma can sometimes spread to other parts of the body – most often to the liver , but also to the lungs and bones . It is important to let your specialist know if you notice any new symptoms, wherever they are in the body, as often further treatment can be given.
Your feelings

During your diagnosis and treatment of cancer you are likely to experience a number of different emotions| , from shock and disbelief to fear and anger. At times these emotions can be overwhelming and hard to control. It is natural and important to be able to express them.

Each individual has their own way of coping with difficult situations; some people find it helpful to talk to friends or family, while others prefer to seek help from people outside their situation. Some people prefer to keep their feelings to themselves. There is no right or wrong way to cope, but help is available if you need it.

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