Retinoblastoma is cancer that starts in the retina of the eye. Retinoblastoma is most common in children and usually diagnosed before age five. Approximately 1 in every 18,000 babies born will develop retinoblastoma, which is between 250 and 500 cases each year in the United States.
The retina is the thin layer of tissue that lines the inside of the eye. When light strikes the retina, it is converted to electrical impulses that are sent through the optic nerve to the brain. Retinoblastoma is a cancerous tumor that grows in the retina. This type of cancer can be inherited (run in families) or may be non-hereditary (sporadic). Patients with the hereditary form may have tumors in one or both eyes, but most cases with tumors in just one eye are non-hereditary. Brothers and sisters of any child with retinoblastoma should have regular eye exams to find out if they may also develop the condition.
Retinoblastoma is usually discovered because someone notices that a child’s eye looks unusual. Symptoms of this type of cancer include:
• White pupil – Normally, the pupil looks like a black circle in the center of the eye. When you shine a light into the eye, such as the flash from a camera, the pupil looks red because of the blood vessels in the back of the eye. But in an eye with retinoblastoma, the pupil may look white or pink instead of red. This condition, which is called leukocoria or cat’s eye reflex, is often first noticed in photographs of the child.
• Lazy eye – Some children with retinoblastoma have strabismus or lazy eye. This means the eyes do not always look in the same direction and may sometimes appear to be crossed. This type of cancer is rarely the cause of lazy eye.
• Blurry vision
• Eye pain
• Redness in the white part of the eye
Stages of retinoblastoma
Before deciding how to treat retinoblastoma, your doctor will need to determine the stage of the cancer. Retinoblastoma is described in these ways:
• Intraocular - This means the cancer is all still inside the eye and has not spread to other tissues
• Orbital – Cancer has spread out of the eye into the eye socket and surrounding tissues on the head.
• Extraocular – This means the cancer has spread outside the eye. It may be orbital or it may have spread to other parts of the body. When cancer spreads this way, it is also called metastatic cancer.
• Recurrent – Cancer that has come back after it was treated is called recurrent cancer. It may reoccur in the eye or in other parts of the body.
Overall, treatment of retinoblastoma has a very high rate of success. However, patients with hereditary retinoblastoma appear to be at increased risk of other types of cancer including bone cancer, soft tissue sarcoma, melanoma, and tumors of the brain. Patients with non-hereditary retinoblastoma do not appear to be at increased risk for other types of cancer.
A subsequent article will discuss available treatments for retinoblastoma.