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EYE CARE :: Eye Disorders


What is retinoblastoma?

Retinoblastoma is a rare cancer of the retina. The retina is the innermost layer of the eye, located at the back of the eye, which receives light and images necessary for vision.

Anatomy of the eye, internal
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About 250 children in the US are diagnosed with this type of cancer each year. It accounts for 3 percent of childhood cancers. Retinoblastoma cells can, in rare cases, spread (metastasize) to other areas of the body, including the bone marrow.

What causes retinoblastoma?

Retinoblastoma occurs due to mutations in a tumor suppressor gene (called RB1) located on chromosome #13. Two mutations (or gene changes) are necessary to "knock-out" this gene, and cause uncontrolled cell growth. In inherited retinoblastoma (40 percent of the cases), the first mutation is inherited from a parent, while the second occurs during the development of the retina. In sporadic retinoblastoma (60 percent of the cases), both mutations occur during development of the retina. Sporadic means "occurs by chance." Alterations in the RB1 gene have also been found in other tumors, including osteosarcoma and breast cancer.

Most children with inherited retinoblastoma generally have tumors involving both eyes. (In fact, all cases involving both eyes should prompt an investigation for a hereditary cause). The RB1 gene is an autosomal dominant gene, which means that both males and females are equally affected, and there is a 50/50 chance, with each pregnancy, for a genetically affected parent to transmit the gene to a child. When a child inherits the gene, there is a 75 to 90 percent chance for the second mutation to occur, resulting in retinoblastoma. This means that some children who inherit the mutation may never get the second mutation, and may, therefore, never develop retinoblastoma. (They can still transmit the gene to their offspring, however, so that their children could develop the disease.)

Consider the following statistics:

  • Sixty percent to seventy-five percent of retinoblastoma cases involve one eye (unilateral). Of these, about 15 percent are inherited, and the remaining 60 percent are sporadic.
  • Twenty-five percent of retinoblastoma cases are bilateral (both eyes) and almost always inherited.
  • Fifteen percent of retinoblastoma cases are unilateral (one eye) and inherited.

Any individual with a positive family history of retinoblastoma should seek genetic counseling to identify the specific risks of passing the gene or disease to their children.

What are the symptoms of retinoblastoma?

The following are the most common symptoms of retinoblastoma:

  • leukocoria - a white light reflex that occurs at certain angles when light is shown into the pupil.
  • strabismus (Also called wandering eye or crossed-eyes.) - a misalignment of the eyes; when one or both eyes do not appear to be "looking" in the same direction.
  • loss of vision in the affected eye

Often the symptoms may not appear if the disease is diagnosed early. The symptoms of retinoblastoma may resemble other conditions or medical problems. Always consult your child's physician for a diagnosis.

How is retinoblastoma diagnosed?

In addition to a complete medical and physical examination, diagnostic procedures for retinoblastoma may include:

  • complete eye examination
  • fundoscopic examination - the pupils are dilated so the entire retina can be viewed and examined.
  • computed tomography scan (Also called a CT or CAT scan.) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.
  • magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.
  • blood tests
  • genetic and/or DNA testing

A diagnosis may be made before symptoms are present. If a family history is positive for retinoblastoma, frequent eye examinations may be necessary at many stages of the child's development to determine the presence of any tumor. When retinoblastoma is diagnosed, tests will be performed to determine the size, number, location of the tumors, and if the tumors have spread to the other parts of the body. This is called staging and is an important step toward planning a treatment program.

Treatment for retinoblastoma:

Treatment may include one or more of the following:

  • surgery (laser treatment (photocoagulation) or freezing probe (cryotherapy) to kill the tumor)
  • enucleation (removal of the eye involved with the tumor)
  • chemotherapy
  • radiation therapy

Rehabilitation may include:

  • fitting and training for a prosthesis
  • blind or decreased vision adaptation training
  • supportive care (for the side effects of treatment)
  • antibiotics (to prevent/treat infection)

Long-term outlook for a child with retinoblastoma:

Prognosis greatly depends on:

  • the extent of the disease.
  • the size and location of the tumor.
  • presence or absence of metastasis.
  • the tumor's response to therapy.
  • the age and overall health of your child.
  • your child's tolerance of specific medications, procedures, or therapies.
  • new developments in treatment.

As with any cancer, prognosis and long-term survival can vary greatly from child to child. Every child is unique and treatment and prognosis is structured around the child's needs. Prompt medical attention and aggressive therapy are important for the best prognosis.

Continuous follow-up care is essential for a child diagnosed with retinoblastoma. Secondary cancers have a high incidence among survivors of retinoblastoma. These secondary cancers are not a relapse or recurrent retinoblastoma, but are primary tumors (brand new tumors) of other organs. The most common secondary cancer is osteosarcoma (cancer of the bone). However, retinoblastoma has been linked to melanoma, breast, lung, bladder, and other types of cancers much later in life.

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It is important to remember the health information found on this website is for reference only not intended to replace the advice and guidance of your healthcare provider. Always seek the advice of your physician with any questions you may have regarding a medical condition. If you think you may have a medical emergency, call your physician or 911 immediately.

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