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Retinoblastoma is a cancer of the eye. It most often occurs in young children, usually before 3 years of age. This cancer rarely develops in children older than age 5. Retinoblastoma forms in the retina of the eye. The retina is a thin layer of nerve tissue in the back of the eye. The cells of the retina detect light and color. Retinoblastoma may affect one eye (unilateral, most common) or both eyes (bilateral).
Retinoblastoma is rare. About 250-300 children are diagnosed per year in the United States. In most patients, retinoblastoma is confined to the eye, and the cancer is very curable. The cure rate for this cancer is above 95% because of early detection and available treatments. If the disease is not treated, it can spread to other parts of the body, where it becomes much harder to treat. Retinoblastoma can be hereditary (passed down in families) or non-hereditary.
Treatments for retinoblastoma include chemotherapy to shrink the tumor, focal therapy (laser or freezing therapy delivered directly to the eye), surgery to remove the eye, and radiation therapy. Patients with the hereditary form of retinoblastoma are also at risk for other cancers later in life.
In most cases, retinoblastoma results from a change (mutation) in a gene known as the retinoblastoma (RB1) gene. When there is a mutation of the RB1 gene, cells grow and divide abnormally.
There are two types of retinoblastoma: non-hereditary (sporadic) and hereditary.
The most common form of retinoblastoma is sporadic, or non-hereditary. Sporadic retinoblastoma is not passed down in families. There is a change in the RB1 gene in a single cell in the retina of one eye. These cells divide and form a tumor. Most patients with only one eye affected (unilateral) have sporadic retinoblastoma.
About 25-30% of children with retinoblastoma have the hereditary form of the condition. Hereditary retinoblastoma is the result of a change (mutation) in the RB1 gene in every cell in the body. Most patients with hereditary retinoblastoma have both eyes affected (bilateral). Children with hereditary retinoblastoma are at risk for developing other cancers later in life. Children with hereditary retinoblastoma may be the first in their families with this gene mutation, and they then have a 50% chance of passing the gene on to their children.
Genetic testing is important in retinoblastoma. Approximately 10-15% of patients with unilateral retinoblastoma and all patients with bilateral retinoblastoma have the hereditary form of the disease. The type of cancer – sporadic or hereditary - can affect treatment decisions and risk of future cancers and may influence future life decisions.
A doctor may discover retinoblastoma during a routine wellness or eye exam. However, many times a parent or relative first notices that a child’s eye looks different from normal. Some of the symptoms of retinoblastoma are common to other eye problems, so it is important to see a pediatric eye doctor for evaluation.
Signs of retinoblastoma include:
If a child shows signs of retinoblastoma, it is important to see a pediatric ophthalmologist (eye doctor for children). An eye doctor may do an office screening exam to determine the need for further testing.
A diagnosis of retinoblastoma is made using an eye exam under anesthesia (EUA). In this test, a doctor (ocular oncologist) examines the eye closely using special lights and a magnifying lens after the eyes are dilated. This procedure is done while the child is asleep so that the doctor can view the entire retina. A special camera takes digital pictures of the eye and tumor.
A biopsy is not used to diagnosis retinoblastoma because this might cause the cancer cells to spread.
In addition to EUA, several types of tests may be used to diagnose and determine the extent of retinoblastoma. These tests include:
If there are concerns that the disease has spread outside the eye, doctors will take samples of the bone marrow and cerebrospinal fluid. Additional imaging tests may be performed to look at the brain and spinal cord.
If retinoblastoma is not treated, it can spread:
Tumors of the eye are “grouped” or classified from Group A to Group E. In the past, retinoblastoma tumors were classified using a numbered grouping system (Group I to Group V), called the Reese-Ellsworth classification.
Grouping describes the likelihood of saving the eye based on tumor size, location, and extent of spread inside the eye. Each eye is graded separately.
Group A tumors are small, and they are located away from the center of vision. Patients with Group A tumors have a good chance of maintaining normal eye function and vision. Group E tumors are large and have broken apart inside the eye (vitreous seeding). Patients with Group E tumors have a higher risk of cancer spreading outside the eye, and children will likely lose vision in the eye.
|Tumor Group||Risk of Losing the Eye||Clinical Features|
|A||Very low risk||Small tumor located only in the retina; not near important structures|
|B||Low risk||Larger tumor and/or located near important structures|
|C||Moderate risk||Tumor is mostly well-defined with small amounts of spread or seeding|
|D||High risk||Tumor is large or poorly defined with high amount of seeding|
|E||Very high risk||Very large tumor that is affecting eye structure and function; higher chance of spread|
The stage of cancer refers to whether it has spread outside the eye. Stage I and Stage II mean the tumor is located only within the eye. Stages 3-4 indicate the tumor has spread to local tissues surrounding the eye or to distant sites (metastatic disease).
Most children with retinoblastoma can be cured. The main factor that influences patient survival is whether the tumor has spread outside of the eye. If it is localized to the eye, the prognosis is excellent. If the cancer has spread to other parts of the body, the illness becomes more difficult to treat.
Several factors influence the outlook for a patient’s treatment and recovery:
Patients with cancer confined to the eye have survival rates >95% with treatment. If the cancer has spread to the eye socket (orbit), lymph nodes, bone marrow, bones or liver, patients have survival rates >80% with intensive chemotherapy, autologous stem cell rescue, and radiation therapy. When cancer has spread to the spinal fluid or other parts of the brain at the time of diagnosis, the prognosis is less favorable (<50% survival).
In the treatment of retinoblastoma, doctors and families must consider how the disease is affecting the child. The focus is first on cure and then on preserving the eye with as much vision as possible. The most important factor for saving the eye is the extent of disease at diagnosis. If there is concern about spread of the disease or concern that treatment is unlikely to preserve meaningful vision, doctors may recommend surgical removal of the eye (enucleation).
In the treatment of patients with retinoblastoma, patient survival is not always the same thing as “eye survival.” The group or classification of the tumor affects prognosis for saving the eye. When tumors are grouped A – C, the eyes and vision are easier to save. Tumors that have broken apart inside the eye with vitreous seeding (Group D or E) are the most difficult to treat.
When tumors are in both eyes (bilateral retinoblastoma), usually an attempt is made to save both eyes, preserving whatever vision is possible. This is successful in about 70-85% of cases. More advanced disease in unilateral retinoblastoma (group D or E) may require removal of the diseased eye and careful monitoring of the remaining healthy eye. Most patients with unilateral retinoblastoma who have surgical removal of the eye will not need any additional treatment.
The therapies used to treat retinoblastoma depend on whether the tumor affects one eye (unilateral) or both eyes (bilateral), the extent of disease within the eye, and whether the tumor has spread to other places in and around the eye. Doctors will also consider other factors including:
Surgery, focal therapy, chemotherapy and/or radiation therapy are used to treat retinoblastoma. Usually, a combination of treatments is used. Before starting therapy, the treatment plan should be discussed with the patient and family in detail to outline risks and benefits, both short- and long- term.
Chemotherapy (“chemo”) uses powerful medicines to kill cancer cells or stop them from growing (dividing) and making more cancer cells. Single medicines or multiple medicines (combination chemotherapy) may be used. Chemotherapy alone cannot cure retinoblastoma. It is used along with other treatments.
Focal therapy refers to therapies that treat the tumor directly. Focal therapies are often used after chemotherapy has been used to shrink the tumor. If the tumor is very small, focal therapy alone may be enough to treat the cancer. These therapies are performed while the child is asleep under anesthesia.
Surgery is used to remove the eye if necessary. Surgery to remove the eye is called enucleation. Among patients with only one affected eye (unilateral retinoblastoma), most (70-90%) do not need any more treatment after surgical eye removal. If the tumor has spread into the tissues surrounding the eye or the eye socket, further testing including bone marrow aspirates and biopsies and lumbar puncture will be performed to determine the overall stage of disease. These patients need systemic chemotherapy due to increased risk of tumor spread. In patients with bilateral retinoblastoma, if one eye is removed, treatment will focus on saving the remaining eye.
Radiation therapy is sometimes used for more advanced cases of retinoblastoma. Radiation uses high-energy waves or other particles to kill cancer cells or stop them from growing. External beam radiation uses a machine outside the body to deliver the radiation to the entire eye. This is the most aggressive treatment for fighting retinoblastoma and may be used to help maintain vision and prevent the spread of the cancer. Because of potential for long-term effects and risk of second cancers, radiation is usually reserved for patients who have spread of disease outside the eye, have not responded to other therapies, or have recurrent disease.
Very rarely, retinoblastoma spreads to the brain, bones or bone marrow. In these cases, more intensive chemotherapy may be needed, followed by autologous bone marrow transplant. Some patients may also require radiation therapy.
Hunter was diagnosed with retinoblastoma at 11 months of age. He was treated with surgical removal of his eye and has been cancer free since. Hunter enjoys all sports and is a great big brother.
Children will receive regular exams including exams under anesthesia (EUA) throughout treatment and for a period of time after treatment. Recurrences can be managed with focal therapy if caught early. The frequency and duration of follow up care are determined by the child’s medical team.
Lifelong follow-up for eye health is important for all survivors of retinoblastoma. Eye exams at least once a year by an ophthalmologist are recommended as part of routine health care. Vision assistance may be needed. If eyesight loss is significant, a referral to a low vision specialist and early introduction to Braille can be helpful. Protective eyeglasses must also be worn to prevent eye injury.
If treatment included surgical eye removal, an orbital implant is placed at the time of surgery. When the socket has healed, the child can be fitted for an artificial eye (prosthesis). Very good cosmetic results can be achieved, as the prosthesis is customized for the patient. Most children who require eye removal have already adapted to changes in vision before surgery, and visual behaviors do not change significantly after enucleation. Yearly exams by an ocularist are recommended for patients with a prosthetic eye.
Patients treated with external beam radiation therapy to the eye are at risk for certain complications, or late effects of therapy. These may include the following eye problems:
Survivors of hereditary retinoblastoma have a greater risk of developing other cancers later in life. This risk is higher if they receive radiation as part of treatment. Young patients are followed with routine brain MRIs until the age of 5 to screen for pineal gland tumors. After age 5, there are no standardized recommendations for routine imaging to screen for second cancers. Patients should tell their primary care providers about their medical history and have annual physician visits (at a minimum) to monitor health.
For general health and disease prevention, all cancer survivors should adopt healthy lifestyle habits, as well as continue to have regular physical checkups and screenings by a primary physician. Survivors who were treated with systemic chemotherapy or radiation should be monitored for acute and late effects of therapy.
Reviewed: June 2018