Retinoblastoma, a cancerous tumor of the retina in the eye, is a rare form of cancer that affects children, most commonly before age 5. The retina is the nerve tissue at the back of the eye that senses light and sends images to the brain, which interprets these images. Retinoblastoma, though rare, is the most common tumor of the eye in childhood years.

The disease affects about one in every 15,000 to 20,000 children. According to the American Cancer Society, retinoblastoma is responsible for 5% of childhood blindness. However, with treatment, 85% of children with retinoblastoma maintain their sight.

Approximately 40% of retinoblastoma cases are hereditary. The hereditary form usually affects younger children (under age 2) and can affect one eye (unilateral) or both eyes (bilateral). However, unilateral retinoblastoma is usually not hereditary and occurs most commonly in older children. All cases of bilateral retinoblastoma are hereditary. Bilateral retinoblastomas can also be associated with a tumor of a small gland in the brain, called the pineal gland tumor.

Children who develop retinoblastoma are more likely to develop other types of cancer later in life. The risk is higher in children with the hereditary type and children who have received radiation therapy or certain types of chemotherapy. Children who develop retinoblastoma in one eye have an increased risk of developing retinoblastoma in the other eye and require frequent eye exams even after treatment. Doctors also recommend that all children with retinoblastoma continue to be checked for other cancers regularly for the rest of their lives. A great proportion of the second cancers that develop in long-term survivors of childhood retinoblastoma can be attributed to the use of radiation therapy treatments use to treat the original retinoblastoma.

Retinoblastoma has received a great deal of study and attention by physicians and scientists involved in the genetics of cancer. There is a specific gene involved in the development of retinoblastoma, hence the high likelihood of inheriting the disease. In the hereditary form of the disease, all of the affected patient's cells have one genetic mutation, which in and of itself is unable to cause the disease to occur. If the patient then develops a second mutation in a susceptible cell in the lining of the eye (the retina), the cancer can develop, and if it does, it is usually bilateral. In the nonhereditary form or sporadic form, both genetic defects occur randomly in the individual and generally result in the formation of a unilateral (only one eye affected) disease.

The heritable form (and the responsible gene) of retinoblastoma can also be associated with several other types of cancer, including cancers of the soft tissues or bone (so called sarcomas) or a very virulent type of skin cancer called malignant melanoma.

The most common sign of retinoblastoma is an unusual whitish appearance of the pupil (a condition known as leukocoria). This condition is seen frequently in children with retinoblastoma, but it does not always indicate retinoblastoma. Children with retinoblastoma also may have a crossed eye (strabismus) that turns out toward the ear or in toward the nose. Strabismus, however, is a common condition and more likely to be noncancerous (benign). About 10% of children with retinoblastoma develop a persistent red irritation and inflammation of the eye. Less common symptoms include differences in iris color and pupil size, tearing, cataract or bulging of the eyes.

Newborns with a family history of retinoblastoma should be examined by an ophthalmologist (eye specialist) before leaving the hospital. In most cases, however, the condition is diagnosed when parents notice an abnormality and bring the child in for examination.

An ophthalmologist diagnoses retinoblastoma through a dilated-pupil examination. This exam involves viewing the retina with an indirect ophthalmoscope to determine if a tumor exists. The indirect ophthalmoscope is different than the hand-held direct ophthalmoscope used by many physicians to look inside the eye. The instrument has more magnifying lenses and allows the physician to see the entire retina more clearly. Most often, this exam is done under general anesthesia so that the physician can look carefully at the child's retina. Sketches or photographs of the view through the ophthalmoscope often are done to map the tumor.

An ultrasound, which uses sound waves to create an image of the internal structures in the eye, often is done to measure larger tumors that make it difficult to see inside the eye. Next, either computed tomography (CT) scans or magnetic resonance imaging (MRI) scans often are done to determine if cancer has spread outside of the eye, into the brain, or to other parts of the body. If cancer spread is seen, additional tests may be needed to confirm whether the cancer has spread to other parts of the body.

Retinoblastoma will continue to grow unless it is treated.

Because retinoblastoma may be hereditary, genetic counseling and testing is an important part of disease management. The American Cancer Society reports that patients who carry the gene for the disease have about an 80% chance of developing retinoblastoma and a 50% chance of passing the gene to a child. Therefore, all siblings and children of retinoblastoma patients should be examined every two to four months during the first years of life.

The type of treatment for retinoblastoma will depend on whether the disease is in one or both eyes, the extent of the disease within the eye, whether vision can be saved, and whether the cancer has spread beyond the eye. This is a rare disease, and you should seek treatment at a center with experience treating this type of cancer.

If the tumor is large, in one eye, and vision cannot be preserved, surgery may be done to remove the whole eye (enucleation). This is a simple operation, and a child usually can be fitted with an artificial eye within about three to six weeks following surgery.

When tumors occur in one or both eyes and there is a chance of preserving vision in one or both eyes, more conservative treatments may be considered. Radiation or chemotherapy may be used to shrink the tumors. The useful chemotherapy drugs include carboplatin, vincrsitine and etoposide. Local treatments such as brachytherapy, photocoagulation and cryotherapy may then be used to eliminate the tumor and preserve vision.

• Radiation � This can be an effective treatment for some patients. Retinoblastoma is very sensitive to radiation. However, there are potential disadvantages. It can damage other tissues inside the eye, eventually leading to cataracts or damaging the retina. In addition, radiation can affect the growth of bone and other tissues near the eye and may increase the patient's risk of developing other cancers. Two types of radiation may be used: external beam radiation, which uses radiation beams focused on the cancer from a source outside the body, and brachytherapy, which involves placing radioactive material into or very near the tumor.



• Photocoagulation � This uses lasers to destroy the tumor.



• Cryotherapy � This is the use of extreme cold to freeze and destroy cancer cells. Cryotherapy is used on small tumors. To be effective, it usually has to be done several times. It is not used when there are several tumors.



• Chemotherapy � Chemotherapy involves an anticancer drug or a combination of drugs that usually are given through an injection into a blood vessel. Retinoblastoma tends to resist chemotherapy, but it may be used effectively in combination with other treatments. For example, it may be used to shrink small tumors in order to increase the chances of success with photocoagulation, cryotherapy or brachytherapy. It is used commonly to treat a child whose tumor has spread beyond the eye. Chemotherapy also may be given to a child when there is no evidence that the cancer has spread beyond the eye, but when the cancer has grown extensively within the eye, which makes it more likely the cancer will spread.

If you see any abnormalities in your child's eyes or vision, immediately take him or her to the doctor for an examination. Your pediatrician may refer you to an ophthalmologist specializing in pediatric eye disease.

Early diagnosis and treatment are crucial to preserving vision and preserving life. The outlook depends on how much the cancer has grown in and beyond the eye. Over the past 20 years, earlier detection and improved treatment methods have greatly enhanced the chances of maintaining vision and have increased the survival rate. The American Cancer Society estimates that more than 90% of children treated for retinoblastoma survive more than five years. Children who still are cancer-free five years after diagnosis and treatment are generally considered cured. However, if left untreated, retinoblastoma is almost always fatal. Survivors have an increased risk of developing a second, unrelated cancer and need close follow-up.

American Cancer Society (ACS)
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National Cancer Institute (NCI)
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