General Information About Retinoblastoma

Retinoblastoma is a disease in which malignant (cancer) cells form in the tissues of the retina.

The retina is made of nerve tissue that lines the inside wall of the back of the eye. It receives light and converts the light into signals that travel down the optic nerve to the brain. The brain decodes the signals so that you can see the image.

Retinoblastoma may be in one eye (unilateral) or in both eyes (bilateral). Cavitary retinoblastoma is a rare type of retinoblastoma in which cavities (hollow spaces) form within the tumor.

Although retinoblastoma may occur at any age, it occurs most often in children younger than 2 years.

Children with a family history of retinoblastoma should have eye exams to check for retinoblastoma.

A child with a family history of retinoblastoma should have regular eye exams beginning early in life to check for retinoblastoma, unless it is known that the child does not have the RB1 gene change. Early diagnosis of retinoblastoma may mean the child will need less intense treatment.

Talk with your child’s doctor about the type of eye exam, how often eye exams are done, and at what age eye exams to check for retinoblastoma can stop.

Retinoblastoma occurs in heritable and nonheritable forms.

A child is thought to have the heritable (inherited) form of retinoblastoma when there is a certain mutation (change) in the RB1 gene. The mutation in the RB1 gene may be passed from the parent to the child, or it may occur in the egg or sperm before conception or soon after conception.

Other factors that suggest the child may have the heritable form of retinoblastoma include the following:

• There is a family history of retinoblastoma.
• There is more than one tumor in the eye.
• There is a tumor in both eyes.

After heritable retinoblastoma has been diagnosed and treated, new tumors may continue to form for a few years. Regular eye exams to check for new tumors are usually done every 2 to 4 months for at least 28 months.

Most cases of retinoblastoma are the nonheritable form. Nonheritable retinoblastoma is not passed down from parents. This type of retinoblastoma is caused by mutations in the RB1 gene that occur by chance after a child is born. Nonheritable retinoblastoma usually occurs in one eye.

A child who has heritable retinoblastoma has an increased risk of trilateral retinoblastoma and other cancers.

A child with heritable retinoblastoma has an increased risk of a pineal tumor in the brain. When retinoblastoma and a brain tumor occur at the same time, it is called trilateral retinoblastoma. The brain tumor is usually diagnosed between 20 and 36 months of age. Regular screening using MRI (magnetic resonance imaging) may be done for a child thought to have heritable retinoblastoma or for a child with retinoblastoma in one eye and a family history of the disease. CT (computerized tomography) scans are usually not used for routine screening in order to avoid exposing the child to ionizing radiation.

Heritable retinoblastoma also increases the child's risk of other types of cancer such as lung cancer, bladder cancer, or melanoma in later years. Regular follow-up exams are important.

Genetic testing can determine whether a child has the heritable or nonheritable form of retinoblastoma.

It is not always clear from the family medical history whether a condition is inherited. Certain families may benefit from genetic counseling and genetic testing. Genetic counselors and other specially trained health professionals can help parents understand the following:

• Their family medical history.
• Their options for RB1 gene testing.
• The risk of retinoblastoma for the child and the child's brothers or sisters.
• The risks and benefits of learning genetic information.

Genetic counselors can also help people cope with their genetic testing results, including how to discuss the results with family members.

Once it is known that the child has heritable retinoblastoma, other family members can be screened for the RB1 mutation. For one specific mutation, the risk of retinoblastoma in a sibling may depend partly on whether the mutation is inherited from the mother or from the father.

Signs and symptoms of retinoblastoma include "white pupil" and eyes that appear to be looking in different directions (crossed eyes).

These and other signs and symptoms may be caused by retinoblastoma or by other conditions. Check with a doctor if your child has any of the following:

• Pupil of the eye that appears white instead of red when light shines into it. This may be seen in flash photographs of the child.
• Eyes that appear to be looking in different directions (crossed eyes).
• Pain or redness in the eye.
• Infection around the eye.
• Eyeball that is larger than normal.
• Colored part of the eye and pupil look cloudy.

Tests that examine the retina are used to diagnose retinoblastoma.

The following tests and procedures may be used:

• Physical exam and health history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken. The doctor will ask if there is a family history of retinoblastoma.
• Eye exam with dilated pupil: An exam of the eye in which the pupil is dilated (opened wider) with medicated eye drops to allow the doctor to look through the lens and pupil to the retina. The inside of the eye, including the retina and the optic nerve, is examined with a light. In young children, this exam may be done under anesthesia.

  There are several types of eye exams that are done with the pupil dilated:

  • Ophthalmoscopy: An exam of the inside of the back of the eye to check the retina and optic nerve using a small magnifying lens and a light.
  • Fluorescein angiography: A procedure to look at blood vessels and the flow of blood inside the eye. An orange fluorescent dye called fluorescein is injected into a blood vessel in the arm and goes into the bloodstream. As the dye travels through blood vessels of the eye, a special camera takes pictures of the retina and choroid to find any blood vessels that are blocked or leaking.
  • Electroretinography: An eye test that uses light and small electrodes to study the retina (the light-detecting part of the eye). This test measures and records the faint electrical signals given off by the cells in the retina when exposed to different types and amounts of light. It can be used to assess the function of the retina during and after treatment.
• RB1 gene test: A laboratory test in which a sample of blood or tissue is tested for a change in the RB1 gene.
• Ultrasound exam of the eye: A procedure in which high-energy sound waves (ultrasound) are bounced off the internal tissues of the eye to make echoes. Eye drops are used to numb the eye and a small probe that sends and receives sound waves is placed gently on the surface of the eye. The echoes make a picture of the inside of the eye and the distance from the cornea to the retina is measured. The picture, called a sonogram, shows on the screen of the ultrasound monitor. The picture can be printed to be looked at later.
• MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body, such as the eye. This procedure is also called nuclear magnetic resonance imaging (NMRI).

Retinoblastoma can usually be diagnosed without a biopsy.

When retinoblastoma is in one eye, it sometimes forms in the other eye. Exams of the unaffected eye are done until it is known that the retinoblastoma is the nonheritable form.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis and treatment options depend on the following:

• Whether the cancer is in one or both eyes.
• The size and number of tumors.
• Whether the tumor has spread to the area around the eye, to the brain, or to other parts of the body.
• The age of the child.
• How likely it is that vision can be saved in one or both eyes.
• Whether a second type of cancer has formed.
• Whether the cancer is newly diagnosed or has recurred (come back).