Retinoblastoma is a rare cancer of the retina (the innermost layer of the eye, located at the back of the eye, that receives light and images necessary for vision). About 250 children will be diagnosed with retinoblastoma this year. It accounts for 3 percent of childhood cancers.
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 be considered hereditary). 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 parent to transmit the gene to a child. When a child inherits the gene, there is about a 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:
Any individual with a positive family history of retinoblastoma may want to seek genetic counseling to identify the specific risks of passing the gene or disease to their children.
The following are the most common symptoms of retinoblastoma. However, each child may experience symptoms differently. Symptoms may include:
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.
In addition to a complete medical and physical examination, diagnostic procedures for retinoblastoma may include:
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.
There are various staging systems that can be used for retinoblastoma. Always consult your child's physician for more information on staging. One method of staging is the Reese-Ellsworth stages of retinoblastoma:
*The "equator" is an imaginary line that divides the eye into two equal parts.
Specific treatment for retinoblastoma will be determined by your child's physician based on:
The primary goal of treatment is to remove the tumor and prevent metastasis (spreading) of the cancer to other parts of the body.
Treatment may include one or more of the following:
Prognosis greatly depends on the following:
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. The cause of the secondary cancers is not known at this time.
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