What Is Retinoblastoma?

by Carlos Rodriguez-Galindo, M.D.
September 9, 2013

Dr. Rodríguez-Galindo is a member of the St. Baldrick’s Scientific Advisory Committee. His research has been focused on retinoblastoma, bone sarcomas, histiocytic disorders, and rare childhood cancers, and he is currently the Chair of the Rare Tumors Committee at the Children’s Oncology Group (COG).

What is Retinoblastoma?
Retinoblastoma is a cancer of the eye that occurs only in children, and typically in very young children. Two-thirds of retinoblastoma patients are diagnosed before they are 2 years old, and more than 90% are diagnosed before the age of 5.

Retinoblastoma can take two forms:

  • Approximately 75% of children with retinoblastoma have one tumor in one eye. This is called unilateral retinoblastoma, and it usually develops around 2 years of age.
  • About 25% of children with retinoblastoma have tumors in both eyes. This is called bilateral or multifocal retinoblastoma, and it usually develops before age 1.

The difference between these two forms of retinoblastoma is that children with tumors in both eyes have a mutation in the retinoblastoma gene (RB1) that makes them more likely to develop the disease. About 95% of children who have this gene mutation will develop retinoblastoma. Because the retinoblastoma gene is a very important tumor suppressor gene, children with the genetic form of retinoblastoma continue to be at risk for other cancers as they grow.

In 1 in 4 cases, genetic retinoblastoma is inherited from one of the child’s parents, but in most cases, the retinoblastoma gene mutates on its own and is not inherited.

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What are the signs and symptoms of retinoblastoma?
The most common sign of retinoblastoma is a white pupil (leukocoria), which is better seen with direct light, such as with a flash photograph. Usually, a flash causes “red eye” in pictures, but for a child with retinoblastoma, one or both pupils will appear white.

The second most common sign is lazy eye (strabismus). For children who have tumors in both eyes, retinoblastoma may cause more severe vision problems. For example, infants may have trouble following objects with their eyes.

How is retinoblastoma diagnosed?
Retinoblastoma can be diagnosed early with a light reflex examination at a pediatrician’s office. These examinations are meant to detect eye and vision problems, and they should be able to detect retinoblastoma as well.

In countries with more limited resources, retinoblastoma may present in more advanced forms, progressing outside of the eye, and causing complete destruction of the eye.

What treatment options are available for retinoblastoma?
Retinoblastoma treatment requires the help of many different specialists, including ophthalmologists, oncologists, radiation oncologists, occupational therapists, clinical geneticists, and nurses. Their priorities are to cure the cancer and save the life of the child, save the eye, and preserve vision, in that order.

For children with cancer in one eye, removal of the eye (enucleation) is usually recommended. Because the potential for vision in that eye is low, and the other eye has normal function, removing the affected eye can provide excellent chances of cure, usually without the need of chemotherapy.

For children who have an eye removed, the surgeon will use a spherical implant and attach it to the eye muscles to allow the implant to move. After surgery, an ocularist will create an artificial eye to go over the implant, and the results are usually excellent.

The alternative to eye removal is using chemotherapy to kill as much tumor as possible, and then using laser or freezing focal treatments for the remaining tumor. In these cases, chemotherapy can be given either by the vein (systemic chemotherapy) or directly into the eye through the artery that feeds it (intra-arterial chemotherapy).

If the tumor is not very large, chemotherapy combined with focal treatments can provide very good chances of saving the affected eye.

For children with cancer in both eyes, the treatment is a little more aggressive. Doctors will try to preserve both eyes, even with limited vision. To do that, different combinations of chemotherapy and very aggressive focal treatments are used. These children need to be followed and monitored very closely.

Radiation therapy is also effective in controlling retinoblastoma. However, radiation can lead to new cancers in the irradiated area. This is an even bigger risk for children who have the retinoblastoma gene mutation, who are already more likely to develop other cancers. For this reason, radiation therapy is used sparingly.

It is important that children with the genetic form of retinoblastoma are checked regularly for other tumors throughout their lives. It’s also important to educate them so they know about their risk of cancer and the risk of passing the gene mutation on to their children.

How are researchers helping kids with retinoblastoma?
Over the last several years, major progress has been made in our understanding of retinoblastoma. We now have a much better knowledge of the genes involved in the development of retinoblastoma, which has allowed us to identify targets for therapy.

With good multidisciplinary care, cure rates are above 95% in the United States, and in many cases, the affected eye can be saved. Treatments have become less intensive and toxic, particularly with the development of better therapies and the use of intra-arterial chemotherapy.

Even with these excellent cure rates, I hope that pediatric oncology research will dramatically change the treatment of retinoblastoma over the next five years.

Advances in basic research have opened the door for new drugs that target specific abnormalities in retinoblastoma cells, and new methods of delivering drugs to the affected eyes are already changing the way we manage this cancer. I expect that in the next few years, we will be able to deliver less intensive and more effective treatments.

I would also like to see children with retinoblastoma diagnosed earlier, when the tumors are very small and easier to treat. This would make the chances of saving eyes and preserving sight much higher.

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