Retinoblastoma is a cancer of the retina, a light-sensitive layer of tissue in the eye. While it is rare, it is the most common malignant tumor that starts in the eye in children.
Only about 350 retinoblastoma cases are diagnosed each year in the United States. It usually occurs before age five. Most of these cases are in children under two.
Between 25% to 40% of retinoblastoma cases are hereditary. In these cases, the patient has a mutation in a gene known as RB1. When healthy, this gene stops tumors from forming. The mutated RB1 gene allows tumors like retinoblastoma to develop.
In the hereditary form of the disease, the mutation is found in the DNA in every cell of the patient’s body. It is usually inherited from a parent, but it also can be a new mutation that starts with the patient. In both cases, this type of retinoblastoma can be passed down to the next generation. It usually develops before age one.
The other 60% to 75% of cases are sporadic retinoblastoma. In these patients, the RB1 mutation is found only in the cancer cells. This form of the disease is not inherited or passed down. Instead, a single cell mutates seemingly at random. It then begins dividing and eventually grows into a malignant tumor. This type of retinoblastoma is more likely to occur in children over age one.
Types of retinoblastoma
Retinoblastoma is categorized based on whether it is in one eye or two.
Unilateral retinoblastoma affects one eye. It makes up 60% to 75% of cases. About 85% of these are the sporadic form of the disease. The rest are hereditary.
Bilateral retinoblastoma affects both eyes. It is almost always hereditary. Patients with bilateral retinoblastoma are typically diagnosed at a younger age (less than one year old) than those with unilateral disease.
Another type of the disease is primitive neuroectodermal tumor (PNET) retinoblastoma, also called trilateral retinoblastoma. This occurs when an associated tumor forms in primitive nerve cells in the brain. PNET retinoblastoma is only found in children with hereditary retinoblastoma. It affects just 5% of these patients.
Intraocular vs. extraocular
Retinoblastoma is also classified by whether it is confined to the eyeball or eyeballs. Learning whether the cancer has spread outside these structures plays an important role in forming a treatment plan.
Intraocular retinoblastoma can be found in patients with either unilateral or bilateral disease. Intraocular means the tumor has not spread outside the eyeball or eyeballs. Cancer cells may be only in the retina or may be in other parts of the eyeball such as the choroid, ciliary body, or part of the optic nerve.
Extraocular retinoblastoma means the cancer has spread beyond the eyeball or eyeballs. It may be found in nearby tissue (such as the eye socket or orbit) or it may have spread to the central nervous system (brain and spinal cord), liver, the bone marrow or lymph nodes.
Retinoblastoma risk factors
A risk factor is anything that increases your chance of developing a disease. Risk factors for retinoblastoma include:
- Age: Most retinoblastomas are diagnosed in children age five and under, typically before age two.
- Family history: Retinoblastoma can be caused by a mutation in the RB1 gene, which suppresses tumor formation. This mutation can be passed down from parent to child.
Learn more about retinoblastoma:
Some cases of retinoblastoma can be passed down from one generation to the next. Genetic counseling may be right for you. Learn more about the risk to you and your family on our genetic testing page.
Retinoblastoma: 7 insights on this rare eye cancer
Retinoblastoma is a cancer that forms in the retina, a layer of tissue in the eye that’s sensitive to light. It’s a rare eye cancer, but it’s the most common cancer that starts in the eye in children. It’s typically diagnosed in children under age 2.
We spoke with ophthalmologist and retinoblastoma specialist Dan Gombos, M.D., to learn more about retinoblastoma, including symptoms, how it’s diagnosed and how it’s treated.
What causes retinoblastoma?
Each retina cell normally has two retinoblastoma genes, called RB1 genes, involved in cell division. If a cell loses both copies of the RB1 gene, you can develop retinoblastoma.
About 40% of cases are germline. This means either a child inherits this gene mutation from one of their parents, or a child develops a new gene mutation spontaneously. In these cases, retinoblastoma can be passed down to the next generation. In most germline cases, children have retinoblastoma in both eyes. This is called bilateral retinoblastoma.
About 60% of cases are caused by a sporadic gene mutation. In these cases, retinoblastoma is not inherited and cannot be passed down to the next generation. This will almost always be unilateral retinoblastoma, affecting only one eye.
Is genetic testing recommended for retinoblastoma?
Yes, it’s our standard to refer patients with retinoblastoma and, at times, their family members, for genetic counseling and genetic testing.
When you have a potential genetic disorder, you’re really referring a family. Families need genetic counseling, especially young parents who have a child with retinoblastoma. They often want to know what the odds are that their other children or potential children will develop retinoblastoma. It could be less than 1% in some cases and as high as 45% in other cases. So, whenever you have a genetic disorder that makes you more likely to have cancer, it’s vital to see a geneticist who provides both genetic testing and genetic counseling.
What are the symptoms of retinoblastoma?
The most common symptom of retinoblastoma in the United States is a white reflex in the eye, known as leukocoria. If a photo is taken with the flash on, it will look like a white spot in the center of the pupil. This is an abnormal reflection of light from the retina.
Other symptoms that could indicate retinoblastoma are strabismus (crossed eyes) or a lazy eye.
Several conditions can cause these symptoms in the eye, many of which are not cancer. But they could negatively affect a child’s sight, so it’s important to have your child evaluated by an ophthalmologist, a medical doctor trained in eye surgery, as soon as possible if you notice these symptoms.
How is retinoblastoma diagnosed?
The early signs of retinoblastoma, such as a white reflex in the eye, are usually found when a child visits a pediatrician. If the assessment is concerning, they will refer the child to an ophthalmologist or an ocular oncologist for a diagnostic eye exam, which may include:
- Dilated eye exam: The child will be placed under anesthesia and their pupils will be dilated so the doctor can examine all parts of the eye.
- Ultrasound: The doctor looks for signs of calcium inside the eye, which is often associated with retinoblastoma.
- Fluorescein angiogram: The doctor dilates the child’s eyes and then injects a colored dye into a vein in the arm. Once the dye reaches the blood vessels in the eye, the doctor uses a special camera to examine the retina.
- MRI: The doctor scans the brain and eye socket.
A biopsy is not used to diagnose retinoblastoma because it can potentially harm the eye, and removing tissue from the tumor can cause the cancer cells to spread.
“After the exams and testing are done, the cancer specialist will determine whether it’s retinoblastoma,” says Gombos, stressing the importance of seeing someone with extensive experience diagnosing eye cancers.
How is retinoblastoma treated?
Treatment for retinoblastoma depends on several factors, including how advanced the tumor is.
“Our treatment approach to retinoblastoma is: first, save the child’s life; second, save the child’s eye; and third, save the child’s sight,” says Gombos.
Chemotherapy kills cancer cells, and it can be delivered in different ways to treat retinoblastoma. One way is intra-arterially, in which chemo is delivered through a catheter inserted into a blood vessel in the groin. It then travels to the blood vessels that feed the eye, delivering the chemo directly into the eye. Intravenous means the chemo is injected into a blood vessel and pumped throughout the body. Chemo can also be injected directly into the eye with a needle while a patient is under anesthesia. This method is called intravitreal.
“We use these techniques to salvage the eye and often the sight,” says Gombos. “But if the cancer is not responding, the disease progresses or if there’s concern of the tumor growing near the optic nerve, we may surgically remove the eye. We don’t want to risk it spreading elsewhere.”
If the tumor in the eye is advanced, then there is a potential risk of the tumor spreading. If that’s the case, sometimes we will remove the eye at the beginning and avoid chemotherapy altogether. If the eye is so advanced that the vision will likely not be salvaged, this is often the best option.
“We always discuss the risks and benefits with every type of treatment with the family,” says Gombos. “We factor in everything and determine what’s in the best interest of the child.”
Can you recover from retinoblastoma?
Retinoblastoma is a highly curative disease when caught early. That’s why it’s important to get treatment at a specialized cancer center with specialists who treat this type of cancer.
What research is being done to advance retinoblastoma treatment?
MD Anderson has contributed to several retinoblastoma clinical trials. A new clinical trial is exploring whether intravenous chemotherapy combined with intravitreal chemotherapy will improve the success rates of salvaging the eyes during retinoblastoma treatment.
Experts are also looking at using a liquid biopsy to diagnose retinoblastoma. While this test has been successful in detecting blood cancers and, more recently, solid tumors, experts are trying to figure out if this would apply to eye cancers.
“We’re researching to see if tapping into the aqueous, which is the fluid in the front of the eye, will be helpful in assessing cancer,” says Gombos.
Gombos began researching retinoblastoma during medical school 30 years ago, and he sees a lot of promise in the treatment advances.
“Retinoblastoma is a disease with a lot of hope,” he says. “When I see these advances, I continue to see opportunities for better treatments across the globe.”
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Why choose MD Anderson for retinoblastoma treatment?
At MD Anderson's Children's Cancer Hospital, retinoblastoma patients have access to every treatment for the disease. These include:
- Intra-arterial chemotherapy
- Intravitreal chemotherapy
- Therapy for advanced metastatic disease, including high dose chemotherapy with stem cell rescue
- Proton therapy
- Brachytherapy
- Laser therapy
- Surgery
- Specialized ocular pathology and tissue harvesting
Many of these treatments are offered through our partnership in the Retinoblastoma Center of Houston. This group brings together retinoblastoma experts from four leading institutions in the Texas Medical Center. Together, they provide retinoblastoma patients with the best possible care. Patients benefit from a team of specially trained physicians who follow your child throughout treatment, all the way to survivorship. Patients also have access to clinical trials offering innovative new treatments for retinoblastoma, including trials conducted through the Children’s Oncology Group.
These experts communicate closely with each other, and with you, to ensure comprehensive, personalized care. For patients with particularly complex cases, the Retinoblastoma Center of Houston holds regular tumor board meetings where experts from its four institutions discuss these patients and form customized treatment plans. This group even helps oncologists around the country develop treatments plan for their retinoblastoma patients.
MD Anderson retinoblastoma patients are also supported by a team of health care professionals dedicated to your child's treatment. These include nurses, physician assistants, physical therapists and others.
And at MD Anderson, you are surrounded by the strength of one of the nation’s top ranked cancer centers. We have all the support and wellness services needed to support the whole family, from programs like child life and art-in-medicine for patients, to support groups and social work counseling for caregivers.
Being positive is the best medicine you can take.
MD Anderson's Children's Cancer Hospital