Oncology: Retinoblastoma

What is Retinoblastoma?

Retinoblastoma is an eye cancer that begins in the retina — the sensitive lining on the inside of your eye. Retinoblastoma most commonly affects young children, but can rarely occur in adults.

Your retina is made up of nerve tissue that senses light as it comes through the front of your eye. The retina sends signals through your optic nerve to your brain, where these signals are interpreted as images.

A rare form of eye cancer, retinoblastoma is the most common form of cancer affecting the eye in children. Retinoblastoma may occur in one or both eyes.

What are the symptoms of Retinoblastoma?

The first clue and most obvious symptom are that the eye doesn’t look right. Specifically, its normally black pupil may look white. In a photo, instead of "red-eye," a child with retinoblastoma will have one pupil that glows white when light shines on it.

Others symptoms include:

• An eye or eyes that appear larger than normal
• Cloudiness or discolouration in the centre of the eye
• Eye pain
• Eyes that cross or look in different directions
• Redness in the white of the eye
• Vision problems

These symptoms can also be caused by less serious problems. But have a doctor check out any issues with your child’s eyes as soon as possible.

When to see a doctor?

Make an appointment with your child's doctor if you notice any changes to your child's eyes that concern you. Retinoblastoma is rare cancer, so your child's doctor may explore other more common eye conditions first.

If you have a family history of retinoblastoma, ask your paediatrician when your child should begin regular eye exams to screen for retinoblastoma.

What are the causes of Retinoblastoma?

Retinoblastoma occurs when nerve cells in the retina develop genetic mutations. These mutations cause the cells to continue growing and multiplying when healthy cells would die. This accumulating mass of cells forms a tumour.

Retinoblastoma cells can invade further into the eye and nearby structures. Retinoblastoma can also spread (metastasize) to other areas of the body, including the brain and spine.

In the majority of cases, it's not clear what causes the genetic mutations that lead to retinoblastoma. However, it's possible for children to inherit a genetic mutation from their parents.

Retinoblastoma that is inherited:

Gene mutations that increase the risk of retinoblastoma and other cancers can be passed from parents to children.

Hereditary retinoblastoma is passed from parents to children in an autosomal dominant pattern, which means only one parent needs a single copy of the mutated gene to pass the increased risk of retinoblastoma on to the children. If one parent carries a mutated gene, each child has a 50% chance of inheriting that gene.

Although a genetic mutation increases a child's risk of retinoblastoma, it doesn't mean that cancer is inevitable.

Children with the inherited form of retinoblastoma tend to develop the disease at an earlier age. Hereditary retinoblastoma also tends to occur in both eyes, as opposed to just one eye.

What are the risks or complications?

Children treated for retinoblastoma have a risk of cancer returning in and around the treated eye. For this reason, your child's doctor will schedule follow-up exams to check for recurrent retinoblastoma. The doctor may design a personalized follow-up exam schedule for your child. In most cases, this will likely involve eye exams every few months for the first few years after retinoblastoma treatment ends.

Additionally, children with the inherited form of retinoblastoma have an increased risk of developing other types of cancers in any part of the body in the years after treatment. For this reason, children with inherited retinoblastoma may have regular exams to screen for other cancers.

Prevention of Retinoblastoma?

In most cases, doctors aren't sure what causes retinoblastoma, so there's no proven way to prevent the disease.

Prevention for families with inherited retinoblastoma

In families with the inherited form of retinoblastoma, preventing retinoblastoma may not be possible. However, genetic testing enables families to know which children have an increased risk of retinoblastoma, so eye exams can begin at an early age. That way, retinoblastoma may be diagnosed very early — when the tumour is small and a chance for a cure and preservation of vision is still possible.

If your doctor determines that your child's retinoblastoma was caused by an inherited genetic mutation, your family may be referred to a genetic counsellor.

Genetic testing can be used to determine whether:

• Your child with retinoblastoma is at risk of other related cancers
• Your other children are at risk of retinoblastoma and other related cancers, so they can start eye exams at an early age
• You and your partner have the possibility of passing the genetic mutation on to future children

The genetic counsellor can discuss the risks and benefits of genetic testing and help you decide whether you, your partner or your other children will be tested for the genetic mutation.

 

What is the Diagnosis for Retinoblastoma?

To diagnose this cancer, an eye doctor looks closely at the inside of the eye with a strong light and a magnifying lens. If it looks like there is cancer, the next step is to find out how big the tumour is and whether it has spread. Your child may have one of these tests:

• Eye examination:  Your eye doctor will conduct an eye exam to determine what's causing your child's signs and symptoms. For a more thorough exam, the doctor may recommend using anaesthetics to keep your child still.
• Imaging tests:  Scans and other imaging tests can help your child's doctor determine whether retinoblastoma has grown to affect other structures around the eye. Imaging tests may include ultrasound, computerized tomography (CT) scan and magnetic resonance imaging (MRI), among others.
• Consulting with other doctors:  Your child's doctor may refer you to other specialists, such as a doctor who specializes in treating cancer (oncologist), a genetic counsellor or a surgeon.

The results help doctors choose the best course of action.

What is the Treatment?

The sooner the cancer is found, the greater the chances are that your child’s eyesight can be saved. Doctors usually use a combination of treatments such as:

• Chemotherapy:  Powerful drugs help shrink the tumour ahead of other treatments. If cancer hasn’t spread, the drugs may be injected directly into the eye or into the blood vessels that lead to it. If the cancer is likely to spread or has already spread, your child will probably take the medications by mouth or through a vein so they can work throughout the body.
• Cryotherapy : A touch with a super-cooled metal probe freezes and kills cancer cells. This works best on small tumours near the front of the eye.
• Thermotherapy : A special laser kills cancer cells with heat. Doctors use it by itself on small tumours or along with other treatments for larger tumours.
• Laser Therapy : A different kind of laser targets and destroys the blood vessels that supply the tumour. This works for small tumours in the back of the eye.
• Radiation:  There are two kinds of radiation therapy. For small tumours, a surgeon can sew a disc that has radioactive material inside it onto the eyeball near the tumour. Your child stays in the hospital a few days while it works, and then the disc is removed. Older technology uses a machine to focus beams of radiation on the tumour. This usually is used only if other strategies don’t work.
• Surgery:  If the tumour is very large by the time it’s found, it may not be possible to save the child’s vision. In these cases, the eye may be removed.

It’s nearly impossible for a small child to keep still long enough for a thorough exam, much less when something is being done to the child's eye. Very young patients usually are sedated or put under for exams and treatments.

What to Expect after the surgery?

Retinoblastoma is almost always curable, especially if it hasn’t spread beyond the eye.

Children treated for retinoblastoma need very close follow-up care. Your child will have frequent checkups to watch for signs that cancer has come back.

Frequent checkups are important for other reasons, too. Children who have a damaged gene in every cell can get other types of cancer later in life because the gene doesn’t help stop the cancers the way a healthy gene would. And children who have radiation or chemotherapy treatment are also more likely to have cancer again.

Most of the cancers caused in these ways are treatable if they’re found early.

Doctors recommend genetic tests to see if your child has the kind of gene damage that can be passed down. Parents and siblings should be tested as well.

NEXT STEP

Before you agree to the test or the procedure make sure you know:

• The name of the test or procedure
• The reason you are having the test or procedure
• What results to expect and what they mean
• The risks and benefits of the test or procedure
• What the possible side effects or complications are
• When and where you are to have the test or procedure
• Who will do the test or procedure and what that person’s qualifications are
• What would happen if you did not have the test or procedure
• Any alternative tests or procedures to think about
• When and how will you get the results
• Who to call after the test or procedure if you have questions or problems
• How much will you have to pay for the test or procedure