Retinoblastoma

What is retinoblastoma?

Retinoblastoma is a rare type of eye cancer that begins in the retina, the light-sensitive layer of the eye. This type of cancer usually develops in early childhood, typically affecting children under the age of five. Very rarely, retinoblastoma can occur in adults. 

It can affect one (unilateral) or both eyes (bilateral). It is sometimes, but not always inherited (genetic). It is usuably curable when diagnosed early, but can spread to other parts of the body if not treated.

What causes retinoblastoma?

During the very early stages of eye development when the baby is in the womb, the eyes contain fast-growing cells called retinoblasts. At a certain point, these cells should stop growing and become mature retinal cells. But occasionally, some retinoblasts grow out of control and develop into a cancerous tumour.

In almost all cases, retinoblastoma starts with a change (or mutation) in the RB1 gene. This gene makes a protein that normally helps keep cells from growing out of control.

Each cell normally has two copies of the RB1 gene. As long as a retinal cell has one copy of the gene that is working properly, it will not form a tumour. But when there are mutations in both copies of RB1, it stops the RB1 protein from working in the way it should. This means the cell can start to grow out of control and turn into cancer.

What are the signs and symptoms of retinoblastoma?

Signs of retinoblastoma may include:

• A white pupil that doesn’t reflect light – this is often the first sign of retinoblastoma, and may look like a white reflection or glow in the centre of their eye (the pupil). This is called leukocoria and may be noticeable in photographs taken with a flash if the pupil appears white rather than red.
• Squint – their eyes may appear to be looking in different directions (crossed eyes). This is also known as strabismus.
• Colour change – there may be a change in the colour of the coloured part of their eye (the iris).
• Poor vision – they may experience a deterioration in their sight, usually if both eyes are affected.
• Red or inflamed eye – their eye or eyes may appear red, sore, or swollen.

It can be hard to tell the difference between symptoms of retinoblastoma and other less serious conditions, so it is important to have your child’s eyes tested if you have any concerns.

Most children with retinoblastoma will seem well. Because the condition typically affects children at a very young age, they may not be able to describe the symptoms. 

Is retinoblastoma serious?

In nearly all cases, retinoblastoma is curable when it is diagnosed early. Treatment is very effective and 99 out of 100 children with the condition will be successfully treated. However, if it is not treated promptly, the cancer can spread beyond the eye to other parts of the body. At this advanced stage, the disease can be life-threatening.

Although every effort will be made to avoid it, some children may lose some or all of their sight as a result of treatment for retinoblastoma.

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How is retinoblastoma diagnosed?

There are a number of tests used to diagnose retinoblastoma, including red reflex test, genetic testing, and different scans such as ultrasound, MRI and optical coherence tomography. For some of these tests, the child may need to be drowsy (sedated) or asleep (under general anaesthetic).

• Red reflex test – This test will take place in a darkened room using a magnifying instrument with a light at one end (an ophthalmoscope). The light will be shone into the child’s eyes to check the retina at the back of both of their eyes. The doctor will be looking for a red reflection, which is normal. If there is a white reflection, the child will be referred to a specialist eye doctor (ophthalmologist) for further investigation. The ophthalmologist will repeat the test using eye drops that increase the size of the pupil, which will give them a clearer view of the retina.
• Ultrasound scan – This imaging test may help to confirm whether or not a child has retinoblastoma. Similar to the kind of ultrasound used for pregnancy scans, it uses high-energy sound waves to create images inside the body, such as the inner parts of the eye. A gel is rubbed on the outside of the eyelid and a small ultrasound probe, which scans the eye, is gently placed on the outside of the eyelid. This probe emits sound waves and detects echoes that bounce from the internal tissues of the eye, which are then converted by a computer into an image on a screen.
• Optical coherence tomography (OCT) – This imaging test uses light waves instead of sound waves to build detailed images of the back of the eye.
• Magnetic resonance imaging (MRI) scan – This type of scan  creates detailed images of the inside of the eye using radio waves and strong magnets. Most children with retinoblastoma will have an MRI scan as part of initial investigations.
• Genetic testing – A laboratory test where a sample of blood or tissue is tested to look for changes in the RB1 gene. It is important to find out whether a child’s retinoblastoma is the heritable or non-heritable form of the disease. This is because children with heritable retinoblastoma have an increased risk of developing some other types of cancer later in life.

If retinoblastoma is suspected, the ophthalmologist will refer your child to one of the two specialist retinoblastoma treatment centres (Birmingham Women's and Children's Hospital or The Royal London Hospital).

What are the treatments for retinoblastoma?

There are several treatment options for children with retinoblastoma – the most appropriate treatments will depend on each child’s individual needs. There are several factors to consider, including where the cancer is, whether it is in one or both eyes, its size, how far it has spread, and how many tumours are in the eye.

The main goal of treatment is to eradicate the cancer. Every effort will be made to preserve vision, but unfortunately, some children may lose some or all of their sight as a result of treatment.

Laser treatments

There are two types of laser treatment for retinoblastoma: photocoagulation and thermotherapy (or heat therapy). They both involve the use of a thin, focused beam of light (a laser beam), which is directed through the pupil while the child is under general anaesthetic. The difference is that the laser delivers light at different wavelengths.

Laser therapy is usually used for small tumours towards the back of the eye, and can be used alone or in combination with chemotherapy. It will require a series of treatments at regular intervals and may continue after the chemotherapy courses have been completed.

Cryotherapy

A technique used to freeze small tumours located at the outer edge of the retina. This treatment may be needed more than once. It is performed under general anaesthetic, so your child will not feel any pain during the procedure. An instrument called a cryoprobe is carefully positioned on the outer surface of the eye, overlying the base of the tumour. The cancer cells are destroyed by freezing them.

Surgery (enucleation)

If the tumour is extremely large and the eye is no longer working, it may be recommended for your child to have surgery to remove the eye and part of the optic nerve. This operation is called an enucleation. It is only recommended when other treatments are unlikely to work and/or would put the child’s life at risk. When the eye is removed, a prosthesis (artificial eye) will be fitted a few weeks after surgery.

Chemotherapy

Chemotherapy (drug treatment) may be needed to shrink larger tumours, and may also be used for small tumours. It can be given to the whole body (systemic), to the eye via a blood vessel (intra-arterial), or to the eye via a thin tube in the eye (intra-vitreal). Systemic chemotherapy may be used to shrink a tumour, making it possible to use more localised therapies such as laser or cryotherapy.

Radiotherapy

Radiotherapy uses high-energy X-rays or radioactive particles to kill the cancer cells. There are two main types of radiotherapy: brachytherapy and external beam radiation therapy.

Brachytherapy (also known as plaque radiotherapy) is where a small radioactive disc (known as a plaque) is attached to the outside of the eye near the site of the tumour for up to four days. It works by delivering a high amount of radiation for a defined period of time to kill the cancer cells.

External beam radiotherapy (EBRT) is very rarely used nowadays. A machine is used to directly aim beams of radiation (protons or photons) at the cancer. Proton beam therapy is a type of external radiotherapy that uses a high-energy beam of protons to precisely deliver a dose of radiotherapy to the cancer. As the proton beams stop once they hit the tumour (unlike photons where there is scatter radiation), it reduces the risk of side effects in surrounding health tissues. This treatment is currently only available at specialist facilities in Manchester and London.  

Are there any complications after retinoblastoma treatment?

Nearly all children with retinoblastoma will survive without the cancer returning. However, there is risk of relapse – and so it’s very important to attend regular follow-up appointments.

A small subset of children may experience long-term complications due to their cancer treatment. The risk of these late effects will depend on the specific treatments they received, the doses of treatment, the type of retinoblastoma (heritable or non-inheritable), and the age of the child when treated. They can include:

• Reduced or loss of vision in the affected eye(s)
• Changes to shape and size of the bones around the eye
• Kidney problems
• Heart problems
• Hearing problems
• Slowed or delayed growth and development
• Fertility issues

What can help retinoblastoma?

Retinoblastoma cannot be prevented, but screening tests can detect it early when treatment is more likely to be successful. If a child is at increased risk of retinoblastoma – for example, because one of their parents had the disease – they may be offered regular screening from birth.

After treatment, a child treated for retinoblastoma will require long-term follow-up with a specialist to monitor for any signs of recurrence or late effects from treatment. Regular eye exams, imaging tests, and genetic counselling may be necessary to ensure ongoing health and to address any potential issues early.

What research is there into retinoblastoma?

In recent decades, research on retinoblastoma has led to significant advances in the diagnosis and treatment of the disease. This has led to greatly improved cure rates and fewer side effects. However, not all children are cured, and even those who do may experience long-term treatment-related side effects, so more research is needed.

Fight for Sight is funding groundbreaking research projects into retinoblastoma. For example:

• A team at Newcastle University recently developed a new model of the disease using patient stem cells. The researchers intend to use this model to help accelerate work to identify and test the effectiveness of potential new treatments in the lab, before moving into human trials.
• Researchers at Birmingham’s Children’s Hospital are aiming to develop a safer and less invasive test to reliably diagnose retinoblastoma using small quantities of DNA in eye fluid. As a result, fewer young children would need to undergo a general anaesthetic, which is required for full eye examinations.

See our research projects

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