Eye cancer (retinoblastoma)
Retinoblastoma is a rare type of eye cancer. It most commonly affects children under the age of 5. Between 40 and 50 children develop this type of tumour each year in the UK. Although this can be very distressing and frightening for the child and their parents, over 9 out of 10 (90%) childen are cured with the right treatment.
One or both eyes can be affected. This is called unilateral or bilateral retinoblastoma. Children with one eye affected are usually diagnosed in the first year of life. But those with both eyes affected tend to be diagnosed a bit later, usually between 24 and 30 months. Fewer than 1 out of every 100 children diagnosed are over 5.
Some children are born with a faulty retinoblastoma gene that they inherited from one of their parents. This gene is known as the Rb gene. About 4 out of 10 children diagnosed with this condition (40%) have the inherited type, which often affects both eyes. Although we know that the faulty gene has been inherited we still do not know why this happens. If there is a history of retinoblastoma in your family, children will usually be screened from birth to the age of 5 years.
We don't know what causes the remaining 60% of retinoblastomas. But these non inherited types nearly always only affect one eye.
To understand how this condition develops it helps to know a bit about the eyes and how they work. There are 3 main parts to the eye
- The globe (eyeball)
- The orbit
- The accessory structures (or adnexal structures), including the tear glands and eye lid
The eyeball is filled with a jelly like substance called vitreous humour. It has a lens at the front. The lens is covered by the coloured part of the eye, the iris. These work like the shutter on a camera. They focus the incoming light onto the back part of the eye called the retina. The retina is like the film in the camera. When light hits the retina it transmits a message to the brain via the optic nerve allowing us to see. Retinoblastoma is a cancer of the retina.
When a baby is growing in the womb, the eyes are one of the first things to develop. In the very early stages the eyes have cells called retinoblasts that grow very fast. They later stop growing and develop into mature retinal cells that can detect light. Very rarely the immature retinoblasts continue to grow very fast and do not turn into mature retinal cells. Instead they grow out of control and develop into this cancerous tumour known as retinoblastoma.
If the tumour is not treated the cells will continue to grow and the cancer will fill most of the eyeball. It can also spread to other parts of the eye and begin to block the flow of fluid within the eye. This leads to a build up of pressure inside the eye and can cause loss of vision. Fortunately, most retinoblastomas are found early and successfully treated before they spread outside the eyeball. If they do spread they can go to anywhere in the body including the brain, bones and lymph nodes. They are very difficult to treat once they have spread.
Most children with retinoblastoma seem well. But two common signs that parents first notice in their child are
- The pupil looks odd
- A squint
The pupil may look white, like a cat's eye that is reflecting light. The child may not be seeing as well. Or the eye may be red and inflamed. The children do not usually complain of any pain. In very few cases, a child who is not gaining weight or developing normally might be referred to a specialist children's doctor (paediatrician) for investigations and the abnormal retinoblastoma gene shows up in a blood test.
How retinoblastoma is treated depends on the stage of the tumour. Retinoblastoma has two main stages. In intraocular retinoblastoma the cancer is entirely within the eye. Your child's specialist will stage the tumour more accurately into one of several subgroups depending on the size and position of the tumour within the eye. The second main stage is extraocular retinoblastoma. The tumour has spread beyond the eye and into the tissues surrounding it. It may have spread to another part of the body.
The important thing to realise is that 9 out of 10 children with retinoblastoma are cured. Treatment can include
- Using laser lights (photocoagulation)
- Freezing the tumour (cryotherapy)
- Ultrasound, microwaves or infrared radiation (thermotherapy)
Smaller tumours will need local treatment. That is, treatment just to the eye itself. Your child may have laser therapy, cryotherapy or thermotherapy to destroy the tumour.
Larger tumours can be treated with chemotherapy, radiotherapy or surgery. Your child may have a combination of these treatments.
Slightly larger tumours are usually treated with a type of radiotherapy called brachytherapy. Small radioactive plates (plaques) are stitched in place directly over the tumour. These stay in place for a few days and are then removed. The radiation destroys the tumour.
For a large tumour that hasn't responded well to other treatment, your specialist may suggest radiotherapy to the whole eye. There is information in our eye cancer section about radiotherapy for eye cancer, including a page on side effects of eye cancer radiotherapy. Please note, this section is about eye cancer in adults, but you may find some of the detail about this treatment useful.
Chemotherapy uses drugs to kill cancer cells. Your child may have chemotherapy to try and shrink the cancer, before one of the local treatments listed above. Or the doctor may suggest chemotherapy if there is any risk that the cancer may have spread. There is a whole section about chemotherapy that you might find useful.
Surgery to remove the eye is used if the tumour is very large and the eye is no longer working. Your child will have an artifical eye to replace the lost one. There is information in our eye cancer section about surgery to remove the eye. Please note, this section is about eye cancer in adults, but you may find some of the detail about treatment useful.
The side effects your child will have depend on the type of treatment they have. Your child’s doctor will talk to you about possible side effects. Most parents worry about whether their child will lose their sight. Whenever possible the doctor will try to keep the sight of the eye.
If one eye is affected and the eye needs to be removed the sight in the other eye won’t be affected. Children learn to adapt very quickly and live a normal life going to mainstream school.
If both eyes are affected it is likely that the child will have some loss of sight. This may mean they need to have visual impairment support, either within a mainstream school or in a specialist school.
After whole eye radiotherapy children may develop a cataract. It depends on the type of radiotherapy your child has. Recently, a new technique of giving radiotherapy has been developed which spares the lens and means that cataracts don’t occur so often now.
Another possible side effect of radiotherapy is a dry eye. This is because radiotherapy can damage the tear ducts. Your child will need to use eye drops or artificial tears to keep the eye moist and reduce the chance of infection.
Longer term problems are rare. Radiotherapy can cause a change in the shape of the face. This is because the bones in the radiotherapy area may not grow at the same rate as normal. It is important to remember that most children are cured with treatment.
Very rarely the cancer can come back again. Or another tumour can develop in the centre of the brain. This is called trilateral retinoblastoma and is very rare. The symptoms include headaches, and feeling and being sick. If you are concerned about any symptoms that your child has contact their doctor. Your child will be followed up very closely.
Children who have inherited retinoblastoma can also develop second tumours but this is rare. Your doctor will talk to you about this if your child is at risk.
Because this type of tumour is so rare it is treated in specialist centres. This may be a specialist eye hospital or a major children's cancer centre. These centres have teams of specialists who know a lot about retinoblastoma and the best way to treat it. The staff may also be able to put you in touch with parents of other children who have already been through diagnosis and treatment.
Parents have a lot to think about and are likely to be worried about getting the best treatment for their child. Talk to the doctors or specialist nurses about any worries that you have. They will understand and will want you to feel comfortable and confident with the treatment and care that your child is getting.
The Childhood Eye Cancer Trust is a UK charity for families and individuals affected by retinoblastoma. They offer support, fund research and can put you in contact with other families that have children with this condition.
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