Referral and Diagnosis
Prompt referral to an eye doctor is vital when retinoblastoma is suspected, or when a child is known to be at risk because a parent or sibling had this cancer, or a parent carries a known RB1 mutation.
Referral to an ophthalmologist trained in the treatment of retinoblastoma is essential to ensure optimal care of the child and family.
Before Birth, When There is a Family History
Genetic testing can identify whether children in the family are at risk. If the RB1 gene mutation has been found in the affected relative’s blood, a sample can be taken from the baby through amniocentesis or CVS, to see if they have inherited the gene change.
If a genetic test comes back positive, or testing Is not available, a special obstetrical ultrasound scan can find tumours in the baby’s eyes before birth. If tumours are found, the baby can be delivered prematurely to begin treatment early. However, pre-term diagnosis and treatment is very new, and available at only a small number of highly specialized hospitals around the world.
After Birth, When There is a Family History
When there is a family history of retinoblastoma, a blood sample can be taken from the baby at birth for genetic testing. This can only be done if the RB1 mutation of the affected relative is already known.
If a genetic test comes back positive, or testing Is not available, the child should be regularly checked for signs of the cancer, so that treatment can begin as early as possible if tumours develop.
Eye exams begin immediately after birth, and are often repeated by the ophthalmologist every few days for the first few weeks. They are then done every few weeks for 3 months, reducing gradually to every 6 months until the child is 3-4 years old.
For the first 4-6 weeks, the baby’s eyes can be examined awake in clinic. After 6 weeks, babies become more active, making awake exams difficult. Also, the whole retina cannot be seen clearly with an office exam after about 6 weeks old. So the baby’s eyes should be examined under general anaesthetic (while the child is asleep).
When Retinoblastoma is Suspected
There is no blood test to diagnose retinoblastoma, only genetic testing to predict risk. The ophthalmologist will apply drops to dilate the pupils so he can have a good look at the back of the eye. An ultrasound, eye pressure test and vision test may also be done.
Retinoblastoma is rare among cancers because it can be diagnosed just by what the doctor sees. A biopsy (tissue sample) is not needed, and this type of surgery can actually cause cancer cells to spread outside the eye. Biopsy is only safe after the eye has been removed.
When Retinoblastoma Has Been Diagnosed
Tests are done to find out more about the cancer, such as number, size and position of tumours, and whether cancer has spread outside the eye. This process is called staging and classification, and helps doctors decide which treatments are most appropriate.