Retinoblastoma

Retinoblastoma Overview

Retinoblastoma is a cancerous tumor that grows in the retina, a layer of nerve tissue the back of the eye that senses light and sends images to the brain. Retinoblastoma can affect children of any age; however, it is most common in children under the age of five.

Forms of Retinoblastoma 

Retinoblastoma can occur in two forms:

An inherited form: There are often tumors in either eyes (bilateral), or sometimes only in one eye.

A non-inherited form: There is a tumor only in one eye (unilateral).

What causes Retinoblastoma?

Inherited retinoblastoma is caused by a genetic abnormality, which accounts in about 40 percent of cases. This is due to an abnormal gene, which is passed from a parent to their child allowing for the tumor to develop. People with this gene, knows as the Rb gene also have an increased risk of developing other types of tumors later in life. Not all children of an infected parent will inherit this gene. Children born into families that have a history of retinoblastoma are advised to be screened at an early age so that treatment can be started early if there are signs of a tumor. 

Screening is advised shortly after birth, and should be repeated every few months up until the age of five. Screening is conducted by an eye specialist who examines the eye, whilst shining a light into it with an ophthalmoscope. 

The cause / causes of retinoblastoma remain unknown. The genetic abnormality of the inherited for is now well understood.

Signs and Symptoms

Screening can detect retinoblastoma, even if a child shows no symptoms. Usually the first sign of retinoblastoma is a white pupil that does not reflect light (leucocoria). This can usually be detected in a photograph of a child that has been taken using flash photography. The affected eye may look white in the photograph. Some children may even have a squint or a painful red eye if the tumor is large. 

Diagnosis

Tests may involve an examination under anesthetic (EUA) in which an ophthalmologist examines the child's eye while they are asleep. Retinoblastoma can usually be diagnosed by its appearance, usually not requiring a biopsy. Further EUAs may be carried to check on the progress of the treatment. 

Once retinoblastoma has been diagnosed, other tests may be conducted to check the exact position, size, and whether it has begun to spread. This is known as staging:

An ultrasound scan may be used to examine the eye and surrounding area.

An MRI scan is a series of detailed images that show the structure of the eye and brain.

A lumbar puncture may be used to examine some of the fluid from around the brain and spinal cord to see if there are any tumor cells present.

A bone marrow sample may be taken to check if there has been any spread of the cancer to the bone marrow. Some children may also need a bone scan to examine the bones more closely.

A blood test may be taken for genetic testing for the Rb gene. Results for this test may take several months.

Staging

Staging is used to describe the size of the cancer and whether it was spread beyond its original site in the body. Knowing the particular type and size of the cancer helps doctors determine the most appropriate treatment. Two common staging systems used to track progress are known as: 

Intraocular retinoblastoma: When there is cancer in one or both of the eyes, but it has not yet begun to spread. 

Extraocular retinoblastoma: The cancer has spread beyond the eye and into the tissue surrounding it or to other parts of the body. 

If the cancer returns after initial treatment, it is known as recurrent cancer. It may also reoccur in other parts of the body.

Treatment

Treatment depends on the number, size and position of the tumors in the eye. The aim of the treatment is to get rid of the cancer and keep the sight in the eye. Depending on the treatment some patients may lose partial eyesight.

Small tumors- 

For small tumors treatment is given in the eye itself by one of the following methods:

Cryotherapy This is used to freeze the tumors, sometimes more than one session is required.

Laser therapy A laser is used to vaporize the tumor, two or three sessions may be needed at monthly intervals.

Plaque For slightly larger tumors and tumors that have not been successfully treated by other methods. A small radioactive disc may be stitched over the tumor on the outside of the eye. The disc must stay in place for two to four days in order for the radiation to destroy the cancer cells.

Thermotherapy In this process heat is used to destroy the cancer cells. The heat is produced by a laser which is directed at the tumor. When combined with chemotherapy or radiotherapy treatment can be even more effective.

Large tumors- 

These can be treated in several ways:

Chemotherapy: Anti-cancer drugs are used to destroy the cancer cells. This may be given before local treatments are conducted in order to help shrink the tumor. This can make the treatment more successful, especially if the cancer has, or might spread to other parts of the body.

Radiotherapy: External beam radiotherapy can be given to the whole eye. Radiotherapy treats cancer by using high-energy rays from a cancer machine to destroy the cancer cells while doing as little harm possible to normal cells, although there will be some effect on the surrounding tissue. Radiotherapy is usually the last hope when other treatments have been unsuccessful.

Surgery: If the tumor is very large and the vision in the eye is lost then the eye is likely to be removed. This process is called enucleation and an artificial eye (Prosthesis) is put in place. 

Side Effects of Treatment 

Treatment for retinoblastoma can sometimes cause side effects. Some side effects may only develop many years after treatment. Any side effects will greatly depend on the kind of treatment used. It is advised to discuss the possible side effects with a doctor before treatment.

Follow Up

90% of children with retinoblastoma are cured. Following treatment, an eye specialist will frequently examine the child's eye under anesthetic to ensure that the cancer has not returned. If the retinoblastoma is the inherited form, children are advised to receive genetic counseling once they are old enough to understand it.

Facts about Retinoblastoma

Retinoblastoma affects over 300 children in the United States and approximately 8,200 children globally each year

Contact a CCBF Doctor

If you have any questions or would like to schedule an appointment, please call 212-756-3400 and schedule a visit with Dr. Aledo.

 

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