Retinoblastoma is a rare form of eye cancer typically diagnosed in children before 7 years of age. It develops in the retina, a vital part of the eye that enables us to see colour and light.
It can occur in one (unilateral) or both (bilateral) eyes, though only one eye is affected in around two-thirds (60%) of all cases.
The diagnosis of retinoblastoma in young babies and toddlers may be made during routine eye examinations, following which the child should be referred to an eye specialist (ophthalmologist).
Retinoblastoma is not common. It makes up 2-3% of cancers diagnosed in children. It affects about one in 15,000 to 18,000 children.
There are two types of retinoblastoma
It is important to identify and differentiate between non-inheritable and heritable retinoblastoma as the heritable form carries other health risks that are not found with the non-inheritable form. Family members may also be at risk if the heritable form is identified.
Children with non-inheritable retinoblastoma are usually not at risk of passing down the disease to their children, and their family members are not at risk.
They also have a much lower risk of developing a second retinoblastoma tumour or other cancers, compared to those with heritable retinoblastoma.
Heritable or hereditary cancer makes up about 5-10% of all cases of cancer. Some genes function to protect us from cancer. When they are not working well, it causes hereditary cancer. We refer to genes that are not working well as faulty genes.
Individuals who carry a faulty cancer gene(s) have a higher chance of developing certain cancers over their lifetime compared to the general population. The types of cancers that they may be at increased risk of will depend on the gene(s) involved.
If you have a faulty cancer gene, you may be at increased risk of developing certain cancers. As genes are shared among family, other family members may have inherited the faulty gene and may be at increased risk of cancer too.
Genetic testing is offered to individuals where a hereditary cause of their personal and/or family history of cancer is suspected.
Genes contain the instructions that our body reads to carry out different functions. Genetic testing involves analysing your genes to understand if there are faults (i.e., mutations) that may increase the risk of diseases like cancer.
There are 3 types of results you may receive:
If parents notice one or more of the following features suggestive of retinoblastoma, they should consult an eye specialist as soon as possible.
Heritable retinoblastoma is associated with a faulty RB1 gene present in every cell of the body, which increases the lifetime risk of developing other tumours or cancers.
Note: The conditions associated with a faulty RB1 gene and their risk estimates may change as more information is available.
Heritable retinoblastoma follows a dominant inheritance pattern. This means that having one faulty copy of the RB1 gene can result in an increased risk of cancer. It can affect both males and females.
Everyone has 2 copies of each gene in their body’s cells:
Not all children with heritable retinoblastoma inherited the faulty RB1 gene from one of their parents.
Often, both parents are not carriers but the child has acquired a faulty RB1 gene (de novo) at conception. As this child carries the faulty gene, they can pass it on to their future children, but their other family members would not be at risk.
While most people who have a faulty RB1 gene develop retinoblastoma, some individuals who carry the faulty gene may not develop etinoblastoma or other cancers. Therefore, the disease may present differently among family members.
You should consider genetic testing if you meet one or more of the following criteria:
The genetic test result can help determine if the retinoblastoma is heritable or not.
Medical implicationsIf heritable, it will guide screening for other cancers you may be at risk for.
Familial implicationsYour genetic test result can also help you understand if other family members are at risk of heritable retinoblastoma. They can subsequently consider their own testing (predictive testing) to clarify their carrier status to determine tumour and cancer risks.Family members who have inherited the same faulty RB1 gene may be at increased risk of tumours and cancer and can benefit from management options such as screening (to detect tumours and cancer at an early and manageable stage). Family members who did not inherit the faulty RB1 gene can avoid unnecessary screening and worry. Their children will also not be at risk.
Family planningIndividuals with a faulty RB1 gene can also consider reproductive options and antenatal screening when planning a pregnancy/family.
Retinoblastoma can be cured in most cases, especially for those in which the disease is confined within the eye.
If left untreated, the cancer can spread out of the eye and to other parts of the body, where it becomes much harder to treat or may even result in loss of life. This is why early reporting of unusual symptoms is important.
Your managing doctor(s) will discuss screening recommendations with you in greater detail. The age, onset and frequency of screening may depend on your personal and/or family history of cancer. Screening guidelines may change as more information is known.
If my genetic test result is positive, it means that I have or will have retinoblastoma, or my retinoblastoma will recur.
FALSE. The genetic test result cannot determine the likelihood of cancer recurrence or the presence of cancer. A positive result only indicates an increased risk of getting cancer or a new cancer developing.
If my child tests positive, it means that my grandchildren will also have retinoblastoma.
FALSE. If your child has a positive genetic test result where a faulty RB1 gene is identified, it means each of his/her future children has a 50% (1 in 2) chance of inheriting the faulty RB1 gene.
My child looks a lot like me, so he/she must have inherited the faulty gene(s) since I have it.
FALSE. Genes that govern your appearance are different from the genes that determine the risk of retinoblastoma like RB1.
My child has heritable retinoblastoma and I have two other children, so one will inherit the faulty gene(s) and one will not, because there is a 50% chance.
FALSE.It is recommended for parents of a child with heritable retinoblastoma to undergo predictive testing to determine if he/she has a faulty RB1 gene as well.
If a parent does carry a faulty RB1 gene, all his/her children have a 50% (1 in 2) chance of inheriting the faulty gene. The genetic test result of one child does not impact the chances of the other child having heritable retinoblastoma.
Download the Heritable Retinoblastoma brochure.
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