Retinoblastoma

Retinoblastoma is a cancerous tumor that grows in the retina, a layer of nerve tissue in the back of the eye that senses light and sends images to the brain.

A cancer of early childhood, retinoblastoma can affect developing fetuses in the womb, as well as newborns, babies, toddlers, and children up to 5 years old.

Many parents first see signs of retinoblastoma after noticing that their child’s pupil (the dark circular area in the middle of the iris, the colored part of the eye) appears whitish in bright light. Some parents notice this effect in photographs. This happens because the pupil is translucent; so, retinal tumors that lie behind it may be noticeable.

While the majority of kids who develop retinoblastoma are born with it, most are not diagnosed at birth. The average age at diagnosis is between 12-18 months. When diagnosed, most kids are treated successfully and able to preserve their sight while maintaining good vision.

Causes

Like other forms of cancer, there is a genetic component to retinoblastoma. Kids who carry the genetic mutation (from either a parent or grandparent) usually get more than one tumor and are likely to develop the disease in both eyes. It also usually occurs at a younger age than kids without the mutation. This is called hereditary retinoblastoma.

The remainder of kids who develop the condition ― about 60% ― have no family history of the disease, and will usually get it in just one eye, with much less risk of developing retinoblastoma in the other eye. This is called unilateral retinoblastoma.

Kids with hereditary retinoblastoma in one eye could develop it later in the other eye, so regular checkups of the healthy eye should be done every 2-4 months for at least 28 months. After treatment is completed, follow-up exams should continue until a child is 5 years old.

Signs and Symptoms

A cloudy white pupil, which might look silvery white or yellow in bright light, is often the first sign of retinoblastoma. This is called leukocoria, or “cat’s eye reflex.” Other symptoms include:

• poorly aligned or “wandering” eye, known as strabismus
• reddish pupil, often with pain
• larger-than-normal pupil
• different-colored irises
• poor vision or decreased vision

Many of these symptoms are common side effects of other eye conditions, and don’t necessarily mean a child has retinoblastoma. If your child has any of these symptoms, contact your doctor right away.

Diagnosis

If retinoblastoma is suspected, the doctor will refer your child to a pediatric ophthalmologist, an eye doctor who will examine the retina by dilating the eye, sometimes under general anesthesia. He or she might also order imaging tests, like an ultrasound of the eye, a computerized tomography (CT) scan, or magnetic resonance imaging (MRI), as well as blood tests.

If retinoblastoma is diagnosed, a pediatric oncologist (cancer doctor) will test to see if cancer is anywhere else in the child’s body. He or she might perform blood tests, a spinal tap, or bone marrow biopsy. Live tissue samples, or biopsies, are rarely used to diagnose retinoblastoma because they can cause cancer cells to spread beyond the eye.

Staging

Once doctors have made a diagnosis of retinoblastoma, they use detailed staging systems ― including the St. Jude’s Children’s Research Hospital and Reese-Ellsworth staging systems ― to determine the extent of the cancer and whether it has spread to other parts of the body. Knowing the stage of the disease helps doctors decide how to treat it.

Staging categorizes retinoblastoma that is either intraocular (within the eye) or extraocular (outside the eye):

• Intraocular retinoblastoma is found in one or both eyes but does not extend beyond the eye.
• Extraocular retinoblastoma means the cancer has spread beyond the eye to tissues around the eye or to other parts of the body, such as the brain, spinal cord, bone marrow, or lymph nodes.

Under the St. Jude’s staging system, intraocular retinoblastoma is classified into four stages:

1. Stage I: the tumor is confined to the retina.
2. Stage II: it is confined to the eyeball.
3. Stage III: the cancer has spread to areas in the region around the eye.
4. Stage IV: the cancer has spread through the optic nerve to the brain, or through the blood to soft tissues, bone, or lymph nodes.

The Reese-Ellsworth staging system (an older model of staging developed in the 1960s) classifies retinoblastoma from Group I (cases that are considered the most favorable for saving the eye) to Group V (these cases are unlikely to be controlled with chemotherapy or radiation).

Recently, the National Childhood Cancer Foundation’s Children’s Oncology Group adopted a more modern staging system that considers a child’s disease severity and predicts what type of treatment will be most effective while still preserving the eye.

Treatment

A pediatric ophthalmologist, pediatric oncologist, and radiation therapist will work together to treat a child with retinoblastoma. This team will individualize a plan for each patient based on the extent of the disease within the eye, whether it is in one or both eyes, and whether it has spread beyond the eye.

There are many forms of treatment for retinoblastoma ― all targeted at killing cancer cells. The following treatments, or a combination of treatments, may be recommended:

• Chemotherapy: Tumor-killing medications are given orally, through injection or intravenously (in a vein).
• Intra-arterial chemotherapy: In some cases, doctors are now injecting chemotherapy drugs into the blood vessel that feeds the eye to get the medication to the tumor more directly.
• External beam radiation: Beams of radiation are carefully focused onto the tumor to kill cancer cells.
• Brachytherapy: Radioactive material (little rods or pellets) is placed within the tumor to deliver beams of radiation to specific areas. This form of treatment minimizes the damage to surrounding healthy tissue.
• Radioactive plaques: A disk is implanted in the eye with a dose of radiation applied directly to the tumor site.
• Cryotherapy: Liquid nitrogen or argon gases ― two extremely cold substances ― are used to freeze and destroy diseased tissue.
• Transpupillary thermotherapy: Laser energy (through the use of infrared light) heats up cancer cells and surrounding blood vessels, which kills the cells.
• Photocoagulation: Laser energy is delivered to blood vessels surrounding the tumor, causing blood clots and depriving the cancer cells of nutrients.
• Enucleation: In severe cases of retinoblastoma, the entire eyeball is removed to prevent the spread of cancerous cells to other areas of the body.

During treatment for retinoblastoma, a child will need periodic examinations of the eyes (usually under anesthesia) to confirm the effectiveness of treatment.

Recurrent retinoblastoma is cancer that has returned or continues to grow after treatment. It may occur in the eye, tissues around the eye, or elsewhere in the body. Kids with hereditary cases of retinoblastoma are more likely to develop new tumors years after treatment. Therefore, close follow-up exams are important for these children, who also are at risk for other types of cancer later in life.

Caring for Your Child

Kids treated with chemotherapy might develop flu-like symptoms afterward. Some might feel nauseated, weak, or dizzy after treatment, or run a fever. Those who undergo radiation therapy might feel more tired than usual. Their skin can become reddened or dry in the area being treated. During this time, the doctor may prescribe pain relievers for your child.

Once treatment is over, kids can get back to normal activities if they feel well enough and if the doctor allows. Recovery periods vary, depending on the treatment and the child.

In many cases, kids with retinoblastoma retain the use of both eyes. Children with one eye removed have good vision and receive a prosthetic eye to replace the missing eye. Prosthetic eyes are of such good quality that most people can’t tell which eye is natural and which is prosthetic.

The majority of children treated for retinoblastoma survive and go on to lead normal lives ― in fact, more than 80% of them will retain 20/20 vision. Still, because those with hereditary retinoblastoma have a significant risk of developing secondary cancers, frequent checkups are vital.