Retinoblastoma

Retinoblastoma is a rare type of eye cancer that typically affects young children, usually under 5 years old. It starts in the retina, the light-sensitive tissue at the back of the eye. Early diagnosis and treatment are crucial for saving the child's life, preserving their vision, and preventing the cancer from spreading.

What is Retinoblastoma?

Retinoblastoma is a rare cancer that begins in the retina, the light-sensitive tissue at the back of the eye. It is the most common eye cancer in children, usually affecting those under 5 years old. This condition can impact one eye (unilateral) or both eyes (bilateral), and early detection is key for successful treatment and a positive outcome.

Retinoblastoma is a type of cancer that forms in the retina, which is the specialized tissue at the back of your eye responsible for sensing light. This cancer occurs when cells in the retina grow and multiply uncontrollably. It is considered rare, but it is the most common cancer of the eye found in children. This condition almost always affects very young children, typically before they reach the age of five. In some cases, retinoblastoma develops in only one eye, which is called unilateral retinoblastoma. In other cases, it can affect both eyes, known as bilateral retinoblastoma. The specific type and extent of the cancer guide the treatment approach.

Symptoms

The most common signs of retinoblastoma are a white pupil reflex (leukocoria) visible in photos, and eyes that appear to look in different directions (strabismus). Other less common symptoms can include redness, swelling, or pain in the eye, or a noticeable change in vision. These signs usually appear in young children.

The most common and often first noticeable symptom of retinoblastoma is a white pupil reflex, medically known as leukocoria. This can appear as a white glow in the center of the eye, especially when light shines on it, such as in flash photographs. Instead of the usual "red eye" effect, the pupil might look white, yellow, or even gray. This happens because the tumor reflects light differently than a healthy retina. Another common sign is when the eyes appear to look in different directions, a condition called strabismus or "crossed eyes." This occurs if the tumor affects the child's vision in one eye, causing the brain to favor the other eye. The affected eye may then drift inward or outward. Less common symptoms can include redness or swelling of the eye, eye pain, or a noticeable change in the child's vision. Sometimes, the colored part of the eye (iris) may appear to be a different color in each eye, a condition known as heterochromia. Any of these signs should prompt an immediate visit to a doctor.

Causes & risk factors

Retinoblastoma is caused by a genetic change (mutation) in the RB1 gene, which normally helps control cell growth. This mutation can be inherited from a parent (heritable retinoblastoma) or occur spontaneously in the child's early development (non-heritable retinoblastoma). There are no known environmental or lifestyle risk factors for this condition.

Retinoblastoma develops due to a specific genetic change, or mutation, in a gene called RB1. This RB1 gene is a "tumor suppressor gene," meaning its normal job is to prevent cells from growing out of control. When this gene mutates, it stops working correctly, allowing retinal cells to multiply abnormally and form a tumor. About 1 in 3 children (30-40%) with retinoblastoma have the heritable form. This means the RB1 gene mutation is present in every cell of their body. It can be inherited from a parent who also carries the mutation, or it can be a new mutation that occurs very early in the child's development. Children with heritable retinoblastoma often develop tumors in both eyes (bilateral) and have a higher risk of developing other cancers later in life. The remaining cases, about 2 in 3 children (60-70%), have non-heritable or sporadic retinoblastoma. In these instances, the RB1 gene mutation occurs only in the retinal cells and is not present in other cells of the body. This form usually affects only one eye (unilateral) and does not increase the risk of other cancers. It is important to note that there are no known lifestyle or environmental risk factors that cause retinoblastoma.

How it's diagnosed

Diagnosing retinoblastoma typically involves a thorough eye examination by a specialist, often under anesthesia, to carefully inspect the retina. Imaging tests like ultrasound and magnetic resonance imaging (MRI) are used to confirm the diagnosis, determine the tumor's size and location, and check for any spread. Genetic testing can also identify the specific gene mutation.

If a doctor suspects retinoblastoma, they will usually refer the child to an eye specialist (ophthalmologist) who has experience with eye cancers. The main diagnostic tool is a comprehensive eye examination, often performed while the child is under general anesthesia. This allows the doctor to fully dilate the pupil and use special instruments to carefully examine the entire retina at the back of the eye for tumors. To confirm the diagnosis and gather more information, imaging tests are crucial. An ultrasound of the eye uses sound waves to create images of the tumor, helping to determine its size and whether it has spread within the eye. Magnetic resonance imaging (MRI) provides detailed pictures of the eye and surrounding areas, checking if the cancer has spread beyond the eye to the brain or other parts of the body. Doctors generally avoid computed tomography (CT) scans due to radiation exposure, especially in young children. Genetic testing may also be performed, particularly if there's a family history of retinoblastoma or if tumors are found in both eyes. This test can identify the specific RB1 gene mutation, which helps determine if the condition is heritable and informs future monitoring for the child and genetic counseling for the family. Early and accurate diagnosis is vital for effective treatment.

Treatment options

Treatment for retinoblastoma aims to save the child's life, preserve the eye, and maintain vision, if possible. Options vary based on tumor size and location, including chemotherapy (medication to kill cancer cells), focal therapies like laser or freezing (cryotherapy), radiation therapy, or surgery to remove the eye (enucleation) in advanced cases.

The choice of treatment for retinoblastoma depends on several factors, including the size and location of the tumor, whether one or both eyes are affected, and if the cancer has spread. The primary goals are to save the child's life, then to save the eye, and finally to preserve as much vision as possible. Treatment plans are highly individualized and often involve a team of specialists. Chemotherapy uses powerful medications to kill cancer cells. It can be given systemically (throughout the body), intra-arterially (directly into the artery supplying the eye), or intravitreally (injected directly into the eye). Chemotherapy can shrink larger tumors, making them easier to treat with other methods, or it can be the primary treatment for widespread disease. Focal therapies are used for smaller tumors. Laser therapy (photocoagulation or transpupillary thermotherapy) uses heat from a laser to destroy cancer cells. Cryotherapy involves freezing the tumor to kill the cells. Radiation therapy uses high-energy rays to destroy cancer cells; this can be external beam radiation (from a machine outside the body) or brachytherapy (plaque radiation), where a small radioactive disc is temporarily placed on the eye near the tumor. In cases where the tumor is very large, has spread significantly within the eye, or has not responded to other treatments, surgery to remove the eye (enucleation) may be necessary. If an eye is removed, a prosthetic eye can be fitted, which looks natural and moves with the other eye. Even with enucleation, the child's life is usually saved, and they adapt well.

Recovery & outlook

The outlook for children with retinoblastoma is generally excellent, with over 95% surviving when diagnosed and treated early in developed countries. Recovery involves ongoing monitoring for recurrence and potential long-term effects, especially for those with the heritable form who face a higher risk of developing other cancers later in life.

With early diagnosis and appropriate treatment, the vast majority of children with retinoblastoma have a very positive outlook. In developed countries, the survival rate is over 95%. Many children are able to keep their eyes and maintain good vision, especially when the cancer is caught at an early stage and treated effectively with focal therapies or chemotherapy. Recovery involves a period of close follow-up care. Children will need regular eye examinations to monitor for any signs of recurrence (the cancer coming back) or the development of new tumors. The frequency of these check-ups will gradually decrease over time but often continue for many years. For children with heritable retinoblastoma, lifelong monitoring is essential. Because the genetic mutation is in all their cells, they have an increased risk of developing other types of cancers, such as bone cancer (osteosarcoma) or soft tissue cancers, later in life. Their care team will discuss specific screening recommendations and genetic counseling for the family. While the journey can be challenging, most children with retinoblastoma go on to live full and healthy lives.

When to see a doctor

You should see a doctor immediately if you notice any unusual changes in your child's eyes or vision. Key warning signs include a white pupil reflex (leukocoria) in photos, eyes that appear to cross or look in different directions (strabismus), or any unexplained redness, swelling, or pain in the eye. Early detection is critical for the best outcomes.

It is important to seek medical attention right away if you observe any of the warning signs of retinoblastoma in your child. The most critical sign to watch for is a white reflection in your child's pupil, especially when seen in flash photographs. This white pupil reflex, or leukocoria, can be a key indicator of an underlying issue. Another significant sign is if your child's eyes do not seem to align properly, appearing to look in different directions. This condition, known as strabismus or "crossed eyes," should also be evaluated by a doctor promptly. While strabismus can have other causes, it is a known symptom of retinoblastoma. Additionally, any unexplained redness, swelling, or persistent pain in your child's eye warrants an immediate medical check-up. If your child seems to have difficulty seeing or is frequently rubbing their eyes, these could also be reasons to consult a healthcare professional. Do not delay seeking care, as early diagnosis of retinoblastoma dramatically improves the chances of successful treatment and preserving your child's vision and life.

Frequently asked questions

Is retinoblastoma always inherited?

No, retinoblastoma is not always inherited. While about 1 in 3 cases (30-40%) are heritable, meaning the genetic mutation can be passed down or occurs early in development, the majority of cases (about 2 in 3, or 60-70%) are non-heritable. In non-heritable cases, the genetic change happens only in the eye cells and is not passed to future generations.

Can retinoblastoma affect adults?

Retinoblastoma is overwhelmingly a cancer of early childhood. It almost exclusively affects young children, typically under the age of 5. It is extremely rare for retinoblastoma to be diagnosed in adults. Other types of eye cancers can affect adults, but retinoblastoma is specific to children.

What is the "white pupil" sign in photos?

The "white pupil" sign, or leukocoria, is when the center of a child's eye appears white, yellow, or gray in a flash photograph, instead of the usual red-eye effect. This happens because the retinoblastoma tumor reflects the light from the flash differently than a healthy retina. It is often the first sign parents notice.

Will my child lose their vision if they have retinoblastoma?

Not necessarily. With early diagnosis and treatment, many children with retinoblastoma can have their vision preserved, especially if the tumor is small and located away from the central vision area. However, vision loss can occur if the tumor is large, affects critical parts of the retina, or if the eye needs to be surgically removed (enucleation).

Is retinoblastoma curable?

Yes, retinoblastoma is highly curable, especially when diagnosed and treated early. In developed countries, the survival rate is over 95%. The goal of treatment is to save the child's life, then to save the eye, and finally to preserve vision. Regular follow-up is important to monitor for recurrence.

What is the difference between unilateral and bilateral retinoblastoma?

Unilateral retinoblastoma means the cancer affects only one eye. This is more common in non-heritable cases. Bilateral retinoblastoma means the cancer affects both eyes. This form is typically associated with heritable retinoblastoma, where the genetic mutation is present in all body cells.

Sources

• MedlinePlus — Retinoblastoma
• Mayo Clinic — Retinoblastoma
• Cochrane Library — Retinoblastoma