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What Is Retinoblastoma?

May 11, 2020
6 min read
What is retinoblastoma?

Dr. Chintagumpala’s specific interests include the management of children with all brain tumors, retinoblastoma, bone tumors and kidney tumors. He serves as chair of the Retinoblastoma Sub-Committee for the Children’s Oncology Group and is a leader in conducting clinical trials involving children with brain tumors and Retinoblastoma.

Dr. Rodríguez-Galindo is a member of the St. Baldrick’s Scientific Advisory Committee. His research focuses on retinoblastoma, bone sarcomas, histiocytic disorders and rare childhood cancers.

What is Retinoblastoma?

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

Retinoblastoma can take two forms:

  • Approximately 75% of children with retinoblastoma have one tumor in one eye. This is called unilateral retinoblastoma and 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 of the retinoblastoma gene (RB1) that makes them more likely to develop the disease. This mutation can be detected by testing a blood sample of the affected child. About 95% of children who have this gene mutation will develop retinoblastoma. One of the normal functions of the retinoblastoma gene is to suppress tumors from developing and therefore is known as a tumor suppressor gene. Children with the genetic form of retinoblastoma continue to be at risk for developing other cancers and the risk increases with each decade of life.

In 25% of 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. The affected children can pass this mutation on to their children and their doctors should therefore recommend they have their children screened from birth.

What are the Signs and Symptoms of Retinoblastoma?

The most common sign of retinoblastoma is a white pupil (leukocoria). So, while flash photography commonly produces a “red eye” effect, for those with retinoblastoma, they will instead present with one or both pupils appearing 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. A definitive diagnosis, however, requires an eye doctor to examine the child’s eye while under anesthesia. Biopsy isn’t required and isn’t recommended to make the diagnosis.  

In countries with more limited resources, retinoblastoma is often not diagnosed until it’s evolved to a much more advanced stage. This occurs when retinoblastoma has progressed outside of the eye, resulting in the complete destruction of the eye.

What Treatment Options are Available for Retinoblastoma?

Retinoblastoma treatment requires the help of many different specialists. These include, ophthalmologists, pediatric oncologists, radiation oncologists, occupational therapists, clinical geneticists and nurses. In order of importance, their priorities are to cure the cancer and save the life of the child, save the eye and then preserve the vision.

For children with advanced cancer in one eye, removal of the eye (enucleation) is usually recommended. Since the potential for vision in that eye is low and the other eye functions normally, removing the affected eye provides an excellent chance of cure. This approach usually does not require chemotherapy.

When forced to remove a child’s eye, the surgeon uses a spherical implant and attaches it to the eye muscles. This allows the implant to move. After surgery, an ocularist creates an artificial eye to go over the implant and the results are usually excellent.

The alternative to eye removal utilizes chemotherapy to kill as much tumor as possible and then uses laser or freezing focal treatments on 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).

In less advanced cases, systemic chemotherapy combined with focal treatments is effective. When cases are more advanced however, intra-arterial chemotherapy with or without intra- vitreal (direct injection into the eye) chemotherapy is increasingly utilized.

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, different delivery methods and very aggressive focal treatments are used.

Radiation therapy is also effective in controlling retinoblastoma. However, radiation can lead to new cancers in the irradiated area. This poses an even bigger risk for children with retinoblastoma gene mutation as they’re already more likely to develop other cancers. Radiation therapy is therefore used sparingly.

It’s 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’re aware of their risk of cancer and the potential 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. Knowledge gained in the genes involved in the development of retinoblastoma, has allowed us to better 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, we 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. While new methods of delivering drugs to affected eyes are already changing the way we manage this cancer. In the next few years, we expect to be able to deliver less intensive, more effective treatments.

Our goal moving forward is to diagnose children with retinoblastoma earlier, when tumors are small and easier to treat. This will greatly improve our chances of saving their eyes and preserving their sight.

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