Retinoblastoma is a rare form of eye cancer that is typically diagnosed in small children, often under the age of two, and usually under the age of five. The disease usually affects only one eye, but in about a third of cases, both eyes are affected. In the United States, this type of cancer is diagnosed in 250 to 350 children every year, and is responsible for about 4 percent of all cancers diagnosed in children. With early diagnosis, retinoblastoma is usually curable. The part of the eye affected by the cancer is the retina. The retina is the light-sensitive layer of tissue in the back of the eye that contains rods and cones, the
receptors that convert light into a signal that the optic nerve uses to transmit an image to the brain.
What Are The Symptoms Of Retinoblastoma?
The hallmark of retinoblastoma is leukocoria — a white pupil. One pupil may appear white instead of black, which becomes especially apparent in flash photos. This is also sometimes called the “cat’s eye reflex.” The eyes may also be misaligned, a condition called strabismus, or “crossed eyes.” The symptoms of retinoblastoma include:
- Eye pain
- Red eyes
- Irritated eyes
- Poor vision
What Causes Retinoblastoma?
Retinoblastoma occurs when the cells in the retina do not stop growing during fetal development. The cells replicate out of control and form a tumor. Retinoblastoma can be inherited, but this only accounts for about 45 percent of cases, meaning the majority of cases are not connected to a family history. Retinoblastoma has been tied to an abnormal version of the RB1 gene. Families known to carry an abnormal variant of the RB1 gene are advised to seek genetic counseling. Babies as young as a few weeks can be tested for the presence of the abnormal RB1. Children who test positive for the RB1 variant are typically given regular eye exams, starting a few days after birth and continuing every few months until the age of five.
How Is Retinoblastoma Diagnosed?
In many cases, retinoblastoma is diagnosed after a caregiver notices symptoms and brings the child to an eye doctor for an evaluation. The process of diagnosis begins with an eye examination. Healthcare professionals who are experienced in diagnosing retinoblastoma will often recognize the symptoms. Cancer is typically diagnosed with a biopsy, but a biopsy on the eye is seldom done, especially on a child, because of the potential for complications and loss of sight. Retinoblastoma can sometimes be an inherited condition, so any family history of the disease — or other forms of cancer — is very important to discuss with a healthcare professional. An ocular oncologist may be consulted, and a comprehensive eye examination may be necessary. In some cases, children are sedated in order for this exam to be done.
Based on the results of the history and the physical exam, an oncologist may decide to do an imaging study. Imaging studies are done not only to confirm the diagnosis, but also to determine how big the tumor is, and whether it has spread beyond the retina.
Some tests that may be used to diagnose retinoblastoma are:
- Magnetic resonance imaging (MRI)
- Computed tomography (CT)
- Bone scan
In cases in which the cancer may have spread beyond the eye, other tests may be used to determine whether the cancer has entered the optic nerve, the bone marrow, or the brain. Some of these tests include:
- Spinal tap
- Bone marrow aspiration
What Are The Stages Of Retinoblastoma?
When retinoblastoma is diagnosed, it is classified into one of three major stages. The stage of the cancer will determine the treatment. The stages are:
- Intraocular: In intraocular retinoblastoma, the cancer has not spread beyond the eye.
- Recurrent: This refers to cancer that has resisted treatment or has recurred after it has been treated.
- Extraocular: In this stage, the cancer has spread outside the eye to other parts of the body.
What Is The Treatment For Retinoblastoma?
When diagnosed in its early stage, retinoblastoma has not spread outside the eye and is very treatable — even curable— in 95 percent of cases. Treatment will depend on the stage of the cancer, but generally the least invasive effective treatment will be used.Several forms of treatment may be combined in order to remove or shrink the tumor and to save sight in one or both eyes.
Photocoagulation: This type of treatment for retinoblastoma uses a high-energy laser. The laser is directed through the pupil at blood vessels that are connected to the tumor. Photocoagulation is done under anesthesia, often on an outpatient basis. This is
most effective for smaller tumors, and is usually done several times, with treatments scheduled about a month apart. Complications can include retinal damage.
Cryotherapy: Cryotherapy uses cold — applied to the tumor with a probe — to freeze the cancer cells, and it usually involves several treatments administered about a month apart. It is done while the patient is under anesthesia in an operating room, but patients are often released to go home the same day. Cryotherapy is typically used for smaller tumors, and ones that are closer to the front of the eye. Complications can include eyelid swelling or damage to the retina.
Chemotherapy: Chemotherapy involves administering medications that kill the cancer cells. Chemotherapy can be administered intravenously or orally, or it can be injected into the spinal cord. In some cases, chemotherapy may be used to shrink the tumor before other treatments are attempted. Chemotherapy is associated with numerous side effects, including nausea, vomiting, hair loss, and fatigue, but these are generally less problematic in children than in adults.
Plaque radiotherapy: Radiation may kill cancer cells. For retinoblastoma, the radioactive material is often surgically placed at the location of the tumor in the eye. This treatment requires a hospital stay until the radioactive material is removed. While radiation can prevent the spread of a tumor, it can also cause complications. Radiation is associated with suppressed growth in the bones around the affected eye, loss of vision, and the development of other forms of cancer. Complications may occur several years, even decades, after the completion of the treatment.
Thermotherapy: An infrared laser is used to apply heat to the tumor to kill the cells. The temperature is typically lower than that of a laser used in photocoagulation, which may reduce the potential damage to blood vessels in the retina. Thermotherapy may be administered several times, often about once a month. It is frequently used in conjunction with other treatments, such as chemotherapy or radiotherapy. Complications can include retinal damage, clouding in the lens of the eye, and a change in the size of the iris.
Enucleation: In some cases, if the tumor has destroyed the sight in the eye, the best treatment may be to remove the affected eye. This surgery is done under general anesthesia, but it is often done very quickly and patients may be able to go home the same day. The eye and part of the optic nerve are removed, and an implant is put in place. An artificial eye can be created that will look and move so similarly to a natural eye that it may not be noticeable. This surgery is typically considered only when sight in the eye has already been compromised; every effort will be made to save the eye and preserve vision if there is a
possibility of doing so. Complications can include growth abnormalities in the eye socket, but an implant can help prevent this