Retinoblastoma is a malignant (cancerous) tumor that occurs in the eye. It arises in the part of the eye known as the retina, which is located along the back wall of the inside of the eye.
Retinoblastoma is relatively rare, occurring in one in 15,000 to 16,000 births and often is diagnosed in children who are less than 2 years of age. It more commonly occurs in only one eye.
There are two forms of retinoblastoma: sporadic and heritable. Of retinoblastoma cases, 60 percent are sporadic. There is strong evidence that when retinoblastoma occurs in both eyes, there is a hereditary factor. When an individual has both eyes affected (bilateral retinoblastoma), his or her children have approximately a 45 percent chance of developing retinoblastoma themselves.
Signs and Symptoms of Retinoblastoma
Retinoblastoma is hard to diagnose early because the symptoms are not obvious. You may have been the first to notice a white reflection in your child's pupil called the cat's-eye reflex. This is when you can actually see the tumor as the eye moves and light reflects off the tumor. Sometimes photographs are useful in picking up this abnormal light reflex.
The child may have been squinting or having difficulty focusing both eyes on the same object. This is called strabismus and usually occurs if the tumor is located in or very near the visually most sensitive part of the eye. Symptoms occurring in later stages of the disease include a painful red eye and loss or decrease of vision in the affected eye.
Retinoblastoma is easily confused with other less severe eye conditions, and careful examination is needed for accurate diagnosis. Many times an ophthalmologist may help with the examination, which is done in the operating room so that the entire retina can be examined. This procedure is done under general anesthesia where medication is given so that the child is not conscious and will not feel any pain.
If the examination shows a great amount of disease in one eye, treatment may include removal of that eye. If both eyes are involved, current treatment approaches are available to make every effort to try to save at least one eye. Removal of your child's eye is done only when the disease has progressed beyond hope of saving useful vision.
The treatment depends on the size and location of the tumor and whether the tumor has spread. Rarely, retinoblastoma can spread to places outside of the eye as well. The most common places are the bone marrow, the central nervous system and the bones. After diagnosis, a number of tests will be done to see if the tumor cells have spread. These tests may include a bone marrow aspirate and biopsy, spinal tap, CT scans, MRI and bone scans. Several types of treatment are available. These include surgery, chemotherapy, cryotherapy and laser therapy, and radiation. Surgery and chemotherapy are the most common treatments for retinoblastoma. Cryotherapy and laser therapy are used for small tumors, less than 6mm in size.
Complications of radiation therapy can include slight damage to the blood vessels, which should not reduce vision. Radiation can eventually lead to glaucoma, increased pressure in the eye. Radiation of the lens of the eye can result in cataracts, clouding of the lens of the eye. Radiation also has cosmetic consequences due to effects on orbital bone growth. In advanced cases surgery to remove the effected eye is the usual treatment. Cryotherapy, or freezing of the tumor, with or without chemotherapy, may be used to treat small localized tumors.
When surgery is finished, your child may be given chemotherapy to destroy any remaining traces of disease. Some of the chemotherapy medicines may be carboplatin, etoposide (VP-16), vincristine, cyclophosphamide, ifosfamide, doxorubicin and topotecan. These drugs have all been found to be somewhat effective against retinoblastoma and may be used alone or in combinations for a course of chemotherapy.
Local chemotherapy is used for large tumors. Chemotherapy can be delivered to the tumor by a more direct route via the arteries within the eye. Side effects of this chemotherapy include swelling of the eyelid, bleeding into the eye, eye muscle dysfunction, drooping of the upper eyelid, or harm to the artery.
After the treatment is completed, the child will receive periodic check-ups, including eye examinations under anesthesia and follow-up with an oncologist. If needed, your child can be fitted with a prosthesis or glass eye.
Success in treating retinoblastoma can be measured either by survival or preservation of vision. For disease confined within the eye itself, nearly 95 percent of children survive. Change in the patient’s vision largely depends on the extent of tumor involvement. The prognosis when the tumor has metastasized is not as favorable.
Treatment may be more successful due to early screening of children who have a family history of the disease.