Anatomy of the eye
Your eye is a complex and compact structure measuring about 1 inch (2.5 centimeters) in diameter. It receives millions of pieces of information about the outside world, which are quickly processed by your brain.
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.
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Because retinoblastoma mostly affects infants and small children, symptoms are rare. Signs you may notice include:
- A white color in the center circle of the eye (pupil) when light is shone in the eye, such as when taking a flash photograph
- Eyes that appear to be looking in different directions
- Eye redness
- Eye swelling
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 a 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 pediatrician when your child should begin regular eye exams to screen for retinoblastoma.
Autosomal dominant inheritance pattern
In an autosomal dominant disorder, the mutated gene is a dominant gene located on one of the nonsex chromosomes (autosomes). You need only one mutated gene to be affected by this type of disorder. A person with an autosomal dominant disorder — in this case, the father — has a 50% chance of having an affected child with one mutated gene (dominant gene) and a 50% chance of having an unaffected child with two normal genes (recessive genes).
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 tumor.
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 percent 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.
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.
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 tumor 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 counselor.
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 counselor 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.
Dec. 14, 2018