Retinoblastoma in children

Retinoblastoma Back to top

About 40 cases of retinoblastoma are diagnosed in the UK each year. Most of these occur in children under the age of five, although it can affect children of any age.

Retinoblastoma is a tumour that occurs in the retina. This is the light-sensitive lining of the eye.

Retinoblastoma can occur in two forms:

• a heritable form where there are often tumours in both eyes (bilateral) or sometimes only in one eye
• a non-heritable form where there is a tumour in only one eye (unilateral)

Causes of retinoblastoma Back to top

The heritable form of retinoblastoma, which accounts for about two in every five cases, is caused by a genetic abnormality. This means that an abnormal gene allows the tumour to develop. This abnormal gene may either be inherited from a parent or occur for the first time at an early stage of development in the womb. People with this gene, known as the Rb gene, also have an increased risk of developing other types of tumour later in life.

Genetic counselling and support is available for families in which a member has retinoblastoma. Not all children of an affected parent will inherit this gene. However, all children born into families with a history of retinoblastoma will be offered blood testing and will usually be checked (screened) for signs of retinoblastoma so that treatment can be started early if a tumour does develop.

Screening usually starts shortly after birth and is repeated every few months for five years. An eye specialist examines the eye, whilst shining a light into it with an ophthalmoscope.

The cause, or causes, of retinoblastoma remain unknown. However, the genetic abnormality in the heritable form of the disease is now well understood.

Signs and symptoms Back to top

Some children with retinoblastoma may have no symptoms, but it will be picked up by screening (in children of families with a history of the condition).

If there is no family history of retinoblastoma, the first sign of the condition is often a white pupil that does not reflect the light (leucocoria). This may be detected when a picture of your child is taken using flash photography. The affected eye may look white in the photograph. Some children may have a squint or, if the tumour is large, they may have a painful red eye.

How it is diagnosed Back to top

Tests may involve an examination under anaesthetic (EUA) in which an eye specialist (ophthalmologist) will examine your child’s eye while they are asleep. Unlike nearly all other types of cancer, retinoblastomas can be diagnosed just by their appearance, and taking a tissue sample (biopsy) is not usually necessary. Several more EUAs will be carried out to check on the progress of treatment.

Once a retinoblastoma is diagnosed, other tests may be done to check the exact position and size of the tumour, and whether it has begun to spread into surrounding structures. This is known as staging.

An ultrasound scan may be used, which is a painless scan that uses sound waves to examine the eye and the surrounding area.

An MRI (magnetic resonance imaging) scan is a series of detailed images that show the structures of the eye and brain.

A lumbar puncture| may be used to examine some of the fluid from around the brain and spinal cord (cerebrospinal fluid), to see if there are any tumour cells present.

A bone marrow sample may be taken to check if there has been any spread of the cancer to the bone marrow. Some children may also need a bone scan so that doctors can look more closely for signs of any spread to the bones.

A blood test may be taken for genetic testing for the Rb gene. Results of this test can take some months.

Any tests and investigations that your child needs will be explained to you. Our general information on children’s cancers gives more details of what the tests and scans involve| .

Staging Back to top

The 'stage' of a cancer is a term used to describe its size and whether it has spread beyond its original site in the body. Knowing the particular type and the stage of the cancer helps the doctors to decide on the most appropriate treatment.

A commonly-used staging system for retinoblastoma is described below:

Intraocular retinoblastoma There is cancer in one, or both, eyes but it has not begun to spread to other parts of the eye or into the tissues surrounding the eye. This stage is sometimes sub-divided into five grades (A to E) depending upon the size and position of the tumour, and the extent of any damage to the eye. It gives the doctors more information to help them plan appropriate treatment.

Intraocular retinoblastoma There is cancer in one, or both, eyes but it has not begun to spread to other parts of the eye or into the tissues surrounding the eye. This stage is sometimes sub-divided into five grades depending upon the size and position of the tumour, and the extent of any damage to the eye. It gives the doctors more information to help them plan appropriate treatment.

Extraocular retinoblastoma The cancer has spread beyond the eye and into the tissue surrounding it or to other parts of the body.

If the cancer comes back after initial treatment, it is known as recurrent cancer. It may come back in the eye, the tissue surrounding the eye, or in other parts of the body.

Treatment Back to top

This depends on the number, position and size of the tumours in the eye. The aim of treatment is firstly to get rid of the cancer and secondly to try to keep the sight in the eye. Depending on the treatment, some patients may lose some of their sight.

Smaller tumours

For smaller tumours, treatment is given to the eye itself (local therapy), by one of the following methods:

• Cryotherapy This is used to freeze the tumours. More than one session may be necessary (in which case they are usually done at monthly intervals).
• Laser therapy A laser is used to vaporise the tumour. Two or three sessions may be needed at monthly intervals.
• Plaque For slightly larger tumours, and tumours that have not been successfully treated using other methods, a small radioactive disc can be stitched over the tumour on the outside of the eye. The disc needs to stay in place for up to four days. The radiation destroys the cancer cells.
• Thermotherapy This process uses heat to destroy the cancer cells and may be combined with chemotherapy or radiotherapy , as heat can improve the effectiveness of these treatments. The heat is produced by a laser that is directed at the tumour.

Larger tumours

These can be treated in a number of ways, including:

• Chemotherapy Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. This may be given before the local treatments mentioned above, to help to shrink the tumour. This can make the treatment more successful. Chemotherapy can also be used if the cancer has spread to other parts of the body, or if it is thought that there is a significant risk that it will do so.
• Surgery If the tumour is very large and the vision in the eye is lost, the eye is likely to be removed. This is called enucleation . An artificial eye (prosthesis) is then fitted.
• Radiotherapy External beam radiotherapy can be given to the whole eye. Radiotherapy treats cancer by using high-energy rays from a machine, to destroy the cancer cells while doing as little harm as possible to normal cells, although there will be some effect on the surrounding tissue. Radiotherapy is usually used in situations when other treatments have not been successful.

Side effects of treatment Back to top

Treatment for retinoblastoma often causes side effects, some of which can develop many years later. Your child’s doctor will discuss these with you before treatment starts. Any possible side effects will depend upon the particular treatment being used.

Clinical trials Back to top

Many children have their treatment as part of a clinical research trial| . Trials aim to improve our understanding of the best way to treat an illness (usually by comparing the standard treatment with a new or modified version of it).

Specialist doctors carry out trials for children's cancer. Your child's medical team will talk to you about taking part in a clinical trial (if appropriate) and will answer any questions you may have. Written information is often provided to help explain things.

Taking part in a research trial is completely voluntary, and you'll be given plenty of time to decide if it is right for your child.

Follow-up Back to top

At least nine out of every 10 children with retinoblastoma are cured. Following treatment, the eye specialist will frequently examine your child’s eye under anaesthetic to check that the cancer has not come back. Follow-up is usually in a clinic for childhood cancers (a paediatric oncology clinic).

If the retinoblastoma is the heritable form, your child will be given genetic counselling when they are old enough to understand it.

If you have specific concerns about your child’s condition and treatment, it is best to discuss them with your child’s doctor, who knows the situation in detail.

Your feelings Back to top

As a parent, the fact that your child has cancer is one of the worst situations you can be faced with. You may have many different emotions| , such as fear, guilt, sadness, anger and uncertainty. These are all normal reactions, and are part of the process that many parents go through at such a difficult time.

Your child may have a range of powerful emotions throughout their experience of cancer. Our booklet, Peppermint Ward is a storybook for 6–9 year-old children with cancer. It looks at the issues that they and their family may face, and helps them to explore their feelings. You can order the booklet online| .

References Back to top

This section has been compiled using information from a number of reliable sources, including:

• Cancer in Children: Clinical Management (5th ed). Eds PA Voute et al. Oxford University Press, 2005.

For further references, please see the general bibliography| .