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Cancer Medicine :: Retinoblastoma - Childhood

Retinoblastoma - Childhood

General treatment information

Retinoblastoma is rare, so few doctors other than those in specialty eye hospitals and major children’s cancer centers have much experience in treating it. Children with retinoblastoma and their families have special needs that can best be met by these children’s cancer centers. These centers have teams of specialists who know about retinoblastoma and the unique needs of children with cancer. This gives the child the best chance for recovery and, if possible, keeping their sight.

Ask your child’s doctor about finding a children's cancer center near you that has expertise in treating babies and children with this rare form of cancer. Ask about the services offered at your treatment center. Your child’s doctor or nurse can tell you what is available to help with any problems you or your child might have.

Children with retinoblastoma are treated by a team of doctors that includes ophthalmologic oncologists (doctors who diagnose and treat eye cancers), pediatric oncologists (doctors who treat children with cancer), and radiation oncologists (doctors who use radiation to treat cancer), as well as the child’s pediatrician. The team will also include other doctors, nurses, therapists, child psychologists, social workers, genetic counselors, and other professionals who have essential roles in helping retinoblastoma patients and their families with recovery after treatment is finished.

There is a lot for you to think about when choosing the best way to treat or manage your child’s retinoblastoma. Often you may have more than one treatment to choose from. You may feel that you need to make a decision quickly. But give yourself time to absorb the information you have learned. Talk to the cancer care team. 

Treatment principles

The goals of treatment for retinoblastoma are:

To get rid of the cancer and save the child’s life

To save the eye if possible

To preserve as much vision as possible

To avoid second cancers, which may also be caused by treatment, particularly in children with hereditary retinoblastoma

The most important factors that will help determine treatment are:

Whether the tumor is just in one eye or both

How good the vision is

Whether the tumor has extended beyond the eyeball

Overall, more than 9 in 10 children can be cured of retinoblastoma. The chances of long-term survival are much better if the tumor has not spread beyond the eyeball.

Depending on the stage of the tumor and other factors, one or more of the following types of treatment may be used:

Surgery

Radiation therapy (brachytherapy or external beam radiation therapy)

Photocoagulation (using lasers to kill small tumors)

Cryotherapy (using small, very cold probes to freeze and kill small tumors)

Thermotherapy (using heat to kill small tumors)

Chemotherapy

The next few sections describe these treatments in more detail and discuss which treatments may be used in different situations.

Surgery for retinoblastoma (enucleation)

Surgery is not needed for all retinoblastomas, especially for smaller tumors. But if a tumor gets quite large before it is diagnosed, vision in the eye has often already been destroyed, with no hope of getting it back. The usual treatment in this case is an operation to remove the whole eye, plus part of the optic nerve attached to it. This operation, known as enucleation, is done while the child is under general anesthesia (in a deep sleep).

During the same procedure, an orbital implant is usually put in to take the place of the eyeball. The implant is made out of silicone or hydroxyapatite (a substance similar to bone). It is attached to the muscles that moved the eye, so it should move the same way as the eye would have. The operation itself often takes less than an hour, and your child may be able to leave the hospital the same day.

Within a few weeks, your child can visit an ocularist (a specialist in eye prostheses) to be fitted with an artificial eye, a thin shell that fits over the orbital implant and under the eyelids. The artificial eye will match the size and color of the remaining eye. Once it is in place, it will be very hard to tell it apart from the real eye.

When retinoblastoma occurs in both eyes, enucleation of both eyes would result in complete blindness. If neither eye has useful vision because of damage already caused by the cancer, this is the surest way to make sure all of the cancer is gone. But doctors may advise other types of treatment if there is any chance of saving useful vision in one or both eyes.

Possible side effects: The most obvious side effect of enucleation is the loss of vision in that eye, although in most cases the vision has already been lost because of the cancer.

Removing the eye also can affect the future growth of bone and other tissues around the eye socket, which can make the area look somewhat sunken. Using an orbital implant can sometimes lessen this effect. (Radiation therapy, the other major treatment option in such cases, may cause the same side effect.)

Radiation therapy for retinoblastoma

This treatment uses high energy x-rays or particles to kill cancer cells or slow their rate of growth. Radiation therapy is an effective treatment for some children with retinoblastoma. Compared with surgery, it has the advantage of possibly preserving vision in the eye. But radiation therapy also has some disadvantages. (See “Possible side effects” below.)

Two types of radiation therapy can be used to treat children with retinoblastoma.

External beam radiation therapy

External beam radiation therapy (EBRT) focuses radiation beams from a source outside the body on the cancer. This was once a common treatment for retinoblastoma. But because of the side effects it can cause, it is now most often reserved for cancers that are not well-controlled with other treatments.

Before treatments start, the radiation team takes careful measurements with imaging tests such as MRI scans to determine the correct angles for aiming the radiation beams and the proper dose of radiation.

EBRT is much like getting an x-ray, but the radiation is more intense. Radiation is usually given 5 days a week for several weeks. For each session, your child will lie on a special table while a machine delivers the radiation from a precise angle. The procedure itself is painless.

Each actual treatment lasts only a few minutes, but the setup time – getting your child into place for treatment – usually takes longer. The child’s head is positioned in a custom-fitted mold that is similar to a cast used to treat broken bones. Young children may be given medicine to make them fall asleep so they will not move during the treatment.

Newer forms of radiation therapy: Many centers now use newer types of external radiation therapy, which are able to target the tumor more precisely. This lowers the doses that surrounding normal tissues get, which may help reduce side effects.

For example, intensity modulated radiation therapy (IMRT) lets doctors shape the radiation beams and aim them at the tumor from several angles, as well as adjust the intensity (strength) of the beams to limit the dose reaching the nearby normal tissues. This may let the doctor deliver a higher dose to the tumor, while reducing side effects. Many major hospitals and cancer centers now use IMRT.

Another newer technique is proton beam therapy. Protons are positive parts of atoms. Unlike the x-rays used in standard radiation, which release energy both before and after they hit their target, protons cause little damage to tissues they pass through and then release their energy after traveling a certain distance. This means that proton beam radiation may be able to deliver more radiation to the tumor and cause less damage to nearby normal tissues. Early results with proton beam therapy are promising, but it is still fairly new, and there is very little long-term data on its use for retinoblastoma. The machines needed to make protons are expensive, and there are only a handful of them in use in the United States at this time.

Possible side effects: Some of the side effects of EBRT will go away after a short while and are not serious. Short-term problems may include effects on skin areas that receive radiation, which can range from mild sunburn-like changes and hair loss to more severe skin reactions.

More importantly, EBRT can damage surrounding normal body tissues. This may eventually lead to cataracts (clouding of the lens of the eye) and damage to the retina or optic nerve, which could reduce vision. Radiation can also interfere with the growth of bone and other tissues near the eye, which can affect the way the area around the eye looks over time.

External radiation therapy can also increase the risk of developing a second cancer in the area. This is especially important in children with the hereditary form of retinoblastoma, who are already at increased risk for developing other types of cancer.

Newer forms of radiation therapy, such as IMRT and proton beam therapy, target the tumor more precisely and spare more normal tissue. This may make some of these side effects less likely than in the past.

Brachytherapy

The use of brachytherapy, also known as internal radiation therapy or plaque radiotherapy, is limited to small tumors. During brachytherapy, a small amount of radioactive material is placed on the outside of the part of the eyeball where the tumor is for a short time. The radioactive material is put in a small carrier (known as a plaque), which is shaped like a very small bottle cap. The plaque is made of gold or lead to shield nearby tissues from the radiation. The radiation travels a very short distance, so most of it will be focused only on the tumor.

The plaque is sewn in place on the eyeball with tiny stitches during a short operation. It is then removed during a second operation several days later. Both procedures are done while the child is under general anesthesia (in a deep sleep). The child typically stays in the hospital during the time between the operations.

Possible side effects: Brachytherapy is less likely to cause side effects than external radiation. The main concern is damage to the retina or optic nerve, which can affect vision. Recent advances in treatment may make this problem less likely. Brachytherapy has not been linked to an increased risk of developing a second cancer.

Laser therapy (photocoagulation) for retinoblastoma

Photocoagulation is a type of laser therapy that uses laser beams aimed through the pupil. The laser is focused on the blood vessels that surround and supply the tumors, destroying them with the heat caused by the beam. Photocoagulation is effective only for smaller tumors.

Your child will be under general anesthesia (in a deep sleep) during the treatment. The treatment is usually given 2 or 3 times, with about a month between treatments.

Possible side effects: In some cases, laser therapy can damage the retina, which can lead to blind spots or temporarily cause the retina to become detached from the back of the eyeball.

Cryotherapy for retinoblastoma

In cryotherapy, the doctor uses a small metal probe that is cooled to very low temperatures, killing the retinoblastoma cells by freezing them. It is only effective for small tumors toward the front of the eye; it is not routinely used for children with several tumors.

The child will be under general anesthesia (in a deep sleep) during the treatment. After the child is asleep, the probe is placed on the outer surface of the eyeball next to the tumor, which is then frozen and thawed several times. Cryotherapy is usually given 2 or 3 times, with about a month between treatments.

Possible side effects: Cryotherapy may cause the eye and eyelid to swell for a few days. As with laser therapy, cryotherapy can damage the retina, which can lead to blind spots or temporarily cause the retina to become detached from the back of the eyeball.

Thermotherapy for retinoblastoma

For thermotherapy, the doctor uses a different type of laser to apply heat to tumor. The temperatures are not quite as high as those used in photocoagulation therapy, so some of the blood vessels on the retina may be spared.

Thermotherapy may be used alone for very small tumors. For larger tumors, it may be used along with chemotherapy (called thermochemotherapy) or with radiation therapy (called thermoradiotherapy). Heat seems to help these other treatments work better.

The treatment is similar to standard laser therapy. It is given while the child is asleep, usually for less than 10 minutes at a time. Typically, 3 treatments are given, about a month apart. When used as part of thermochemotherapy, the heat is usually applied at a lower temperature over a slightly longer period of time, starting within a few hours after chemotherapy.

Possible side effects: Thermotherapy can sometimes cause part of the iris (the colored part of the eye) to shrink. Other possible effects include clouding of part of the eye lens or damage to the retina, which might affect vision.

Chemotherapy for retinoblastoma

Chemotherapy (chemo) uses anti-cancer drugs to treat the retinoblastoma. Chemotherapy can be given in different ways.

Systemic chemotherapy

In most cases, chemo drugs are injected into a vein (IV) or given by mouth. These drugs enter the bloodstream and reach throughout the body. This is known as systemic chemotherapy.

Periocular (subtenon) chemotherapy

For some advanced intraocular cancers, higher doses of chemo are needed inside the eye. Along with systemic chemotherapy, one of the drugs (carboplatin) may be injected in the tissues around the eye, where it slowly diffuses into the eyeball. This is called periocular or subtenon chemotherapy. These injections are done while the child is under anesthesia. They may cause significant redness and swelling around the eye.

Intra-arterial chemotherapy

A newer approach now sometimes used instead of systemic chemotherapy is to inject chemo directly into the ophthalmic artery, the main artery that supplies blood to the eye. In this technique, a very thin catheter (a long, hollow, flexible tube) is inserted into a large artery on the inner thigh and slowly threaded through the blood vessels all the way up into the ophthalmic artery. (This is done with the child asleep under general anesthesia.) The chemotherapy is then infused into the artery. The drug used most often is melphalan, but other drugs such as carboplatin and topotecan can also be used. This process may then be repeated every 3 to 4 weeks, depending on how much the tumor shrinks.

Because the chemotherapy is put directly into the artery feeding the eye, doctors can use much smaller doses of chemo drugs (less than 10% of the doses used for systemic chemo). Therefore, the side effects related to the chemotherapy are minimal.

Early results with this technique in eyes with advanced tumors have been promising, with good tumor control and few side effects in most cases. In most cases it has allowed doctors to save an eye that otherwise would have needed to be removed.

Uses of chemotherapy

There are a few situations in which chemotherapy may be used.

Chemo may be used as the first treatment to shrink some tumors that have not spread outside the eye. This is called chemoreduction. These tumors can then be treated more effectively with focal therapies such as laser therapy, cryotherapy, thermotherapy, or brachytherapy to completely kill the tumor.

Systemic (IV) chemotherapy may also be given to children whose tumors do not seem to have spread beyond the eye, but seem likely to spread because of the size and/or location of the cancer. Chemo is also sometimes used when the eye has already been removed, but the tumor was found to extend into some areas in the eye that make it more likely the cancer may have spread. This type of treatment is called adjuvant chemotherapy.

Systemic chemotherapy is also used to treat children whose retinoblastoma has spread beyond the eye, a much more critical situation. If the cancer has spread to the brain, chemotherapy may be given directly into the fluid that surrounds it, as well. Tumors outside the eye may shrink for a time with standard doses of chemotherapy, but they will usually start growing again. For this reason, doctors often prefer to use a more intense chemo regimen, usually along with a stem cell transplant. 

Doctors give systemic chemotherapy in cycles, with each period of treatment followed by a rest period to allow the body time to recover. Each chemo cycle typically lasts for a few weeks, and the total length of treatment is often several months.

Some of the drugs that can be used to treat children with retinoblastoma include:

Carboplatin

Cisplatin

Vincristine

Etoposide

Teniposide

Cyclophosphamide

Doxorubicin

In most cases, 2 or 3 drugs are given at the same time. A standard combination used for chemoreduction of intraocular retinoblastoma is carboplatin and vincristine, with or without etoposide. Other drugs may be used if these are not effective.

A drug called cyclosporine is sometimes given with chemo. Cyclosporine is not a chemo drug (it does not directly kill cancer cells), but it may make the tumor cells more sensitive to chemo drugs.

Possible side effects

Chemo drugs attack cells that are dividing quickly, which is why they work against cancer cells. But other cells in the body, such as those in the bone marrow (where new blood cells are made), the lining of the mouth and intestines, and the hair follicles, also divide quickly. These cells are also likely to be affected by chemo, which can lead to side effects.

Children seem to do better than adults when it comes to chemo. They tend to have less severe side effects and to recover from side effects more quickly. One benefit of this is that doctors can give them the high doses of chemo needed to kill the tumor.

The side effects of chemo depend on the type and dose of drugs given and the length of time they are taken. General side effects of chemo drugs can include:

Hair loss

Mouth sores

Loss of appetite

Nausea and vomiting

Diarrhea

Increased chance of infections (because of low white blood cell counts)

Easy bruising or bleeding (because of low blood platelet counts)

Fatigue (because of low red blood cell counts)

Most of these side effects are short-term and tend to go away after treatment is finished. There are often ways to lessen these side effects. For example, drugs can be given to help prevent or reduce nausea and vomiting. Be sure to discuss any questions about side effects with your child's cancer care team.

Along with those listed above, certain chemo drugs can cause specific side effects. For example:

Cisplatin and carboplatin can affect the kidneys. Giving the child plenty of fluids during treatment can help reduce this risk. These drugs can also cause hearing loss in young children, especially in babies younger than 6 months. Your child’s doctor may check your child’s hearing with tests during or after treatment. When carboplatin is injected directly into the tissues near the eye (periocular chemotherapy), it can cause redness and swelling in the area.

Vincristine can damage nerves. Some people may feel tingling and numbness, particularly in their hands and feet.

Some drugs used to treat retinoblastoma, such as etoposide, can increase the risk of later developing a cancer of white blood cells known as acute myeloid leukemia. Fortunately, this is not common.

Doxorubicin can cause heart damage. The risk of this happening goes up as the total amount of the drug that is given goes up. Doctors try to reduce this risk as much as possible by not giving more than the recommended doses of doxorubicin and by checking the heart with an echocardiogram (an ultrasound of the heart) during treatment.

Cyclophosphamide can damage the bladder, which can cause blood in the urine. The chance of this happening can be lowered by giving it along with plenty of fluids and with a drug called mesna, which helps protect the bladder.

High-dose chemotherapy and stem cell transplant for retinoblastoma

Doctors are studying the use of this type of treatment in children with retinoblastoma that has spread outside the eye and who are unlikely to be cured with other treatments. A peripheral blood stem cell transplant (PBSCT) lets doctors give very high doses of chemotherapy (higher than could safely be given otherwise). In the past, this type of treatment was commonly referred to as a bone marrow transplant.

The bone marrow is the soft, inner part of some bones where new red blood cells, white blood cells, and platelets are made. Red blood cells carry oxygen to all parts of the body. White blood cells help the body fight off infections. Platelets are needed to help the blood clot to stop bleeding.

The usual doses of chemotherapy drugs can affect quickly dividing cells like those in the bone marrow. Even though higher doses of these drugs might be more effective in treating tumors, they can't be given because they would cause severe damage to bone marrow cells, leading to life-threatening shortages of blood cells.

To try to get around this problem, the doctor may treat the child with high-dose chemotherapy (sometimes along with radiation therapy) and then give a PBSCT to “rescue” the bone marrow.

How is it done?

The first step in a PBSCT is to collect, or harvest, the child’s own blood-producing stem cells to use later. (These are the cells that make the different types of blood cells.) This type of transplant, where the stem cells are taken from the patient (as opposed to coming from someone else), is known as an autologous transplant.

In the past, the stem cells were often taken from the child’s bone marrow, which required a minor operation. But doctors have found that these cells can be taken from the bloodstream during a procedure known as apheresis. This is similar to donating blood, but instead of going into a collecting bag, the blood goes into a special machine that filters out the stem cells and returns the other parts of the blood to the child’s body. The stem cells are then frozen until the transplant. This process may need to be done more than once.

Once the stem cells have been stored, the child gets high-dose chemotherapy, sometimes along with radiation therapy. When the treatment is finished (a few days later), the stem cells are thawed and returned to the body in a process similar to a normal blood transfusion. The stem cells travel through the bloodstream and settle in the bone marrow. Over the next 3 or 4 weeks, the stem cells start to make new, healthy blood cells.

Until this happens, the child is at high risk of infection because of a low white blood cell count, as well as bleeding because of a low platelet count. To avoid infection, protective measures are taken, such as using special air filters in the hospital room and having visitors wear protective clothing. Blood and platelet transfusions and treatment with IV antibiotics may also be used to prevent or treat infections or bleeding problems.

Practical points

A PBSCT is a complex treatment that can cause life-threatening side effects. If the doctors think your child may benefit from a transplant, the best place to have this done is at a nationally recognized cancer center where the staff is experienced in doing the procedure and managing the recovery period.

A stem cell transplant often requires a long hospital stay and can be very expensive, often costing well over $100,000. Because the procedure is so expensive, you should be sure to get a written approval from your insurer before treatment if it is recommended for your child. Even if the transplant is covered by your insurance, your co-pays or other costs could easily amount to many thousands of dollars. It is important to find out what your insurer will cover before the transplant to get an idea of what you might have to pay.

Possible side effects

Possible early complications and side effects are basically the same as those caused by any other type of high-dose chemotherapy , and can be severe. They are caused by damage to the bone marrow and other quickly dividing tissues of the body. Side effects can include:

Low blood cell counts (with fatigue and an increased risk of infection and bleeding)

Nausea and vomiting

Loss of appetite

Mouth sores

Diarrhea

Hair loss

One of the most common and serious short-term effects is an increased risk of infection. Antibiotics often are given to try to keep this from happening. Other side effects, like low red blood cell and platelet counts, may require blood product transfusions or other treatments.

Some complications and side effects can last for a long time or may not occur until years after the transplant. These can include:

Radiation damage to the lungs

Problems with the thyroid or other hormone-making glands

Problems with fertility

Damage to bones or problems with bone growth

Development of another cancer (including leukemia) years later

Be sure to talk to your child's doctor before the transplant to learn about possible long-term effects your child may have.

What happens after treatment for retinoblastoma?

Following treatment for retinoblastoma, the main concerns for most families are the immediate and long-term effects of the tumor and its treatment, and concerns about the possibility of the cancer coming back.

It is certainly normal to want to put the tumor and its treatment behind you and to get back to a life that doesn’t revolve around cancer. But it’s important to realize that follow-up care is a central part of this process that offers your child the best chance for recovery and long-term survival.

Follow-up exams

Once treatment is finished, the health care team will discuss a follow-up schedule with you, including which tests should be done and how often. It is very important to go to all follow-up appointments. Follow-up is needed to check for cancer recurrence, as well as possible side effects of certain treatments. Doctor visits and tests are done more frequently at first. If nothing abnormal is found, the time between tests can then be extended.

If a child with retinoblastoma in only one eye has been treated by enucleation (removal of the eye), regular exams are needed to look for tumor recurrence, spread, or any growth irregularities related to surgery. It is also important to have the remaining eye checked regularly so that if a second retinoblastoma develops later on it can be found and treated as early as possible.

For children treated with radiation therapy, laser therapy, cryotherapy, or treatment other than removal of the eye, close follow-up exams by an ophthalmologist are very important. In children with hereditary retinoblastoma, it is very common for new tumors to form until they are 3 or 4 years old. This is not a failure of the treatment, but the natural process in bilateral retinoblastoma. Therefore, it is very important that even after completing all treatments, children are examined regularly by specialists.

General anesthesia (where the child is asleep) may be needed to keep a young child still enough for the doctor to do a thorough eye exam. This is done to be certain the cancer has been completely destroyed, to find recurrences as early as possible, and to find problems with vision caused by treatments.

It is important for you to report any new symptoms your child is having, such as pain or vision problems, to your doctor right away, since they could be an early warning of cancer coming back or long-term side effects of treatment.

Genetic counseling and testing for retinoblastoma

If you have a child diagnosed with retinoblastoma, your family may be referred for genetic counseling. This is because some cases of retinoblastoma are caused by a genetic mutation that can be inherited.

If a child is diagnosed with retinoblastoma in both eyes, it can be assumed that they have the hereditary form of the disease, which means they carry the mutant RB1 gene in all their cells. It's also possible that children with retinoblastoma in only one eye carry the mutant RB1 gene in all their cells. This can be confirmed with a blood test. Children with this mutant gene are at increased risk for developing cancer later in life. 

If the child carries the mutated RB1 gene, then other children in the family may have inherited the same abnormal gene as well, and are at risk of being affected. Meeting with a genetic counselor can give you a better idea of what this risk might be and if other children in the family should be tested for the mutation. The genetic counselor will:

Review the child’s medical records and ask questions about other relatives to estimate the likelihood of an inherited gene affecting some family members.

Provide information and answer questions about genetic testing, and schedule tests for other children in your family (if needed) so that their risk of developing retinoblastoma can be determined.

If tests show your children are at risk of developing retinoblastoma, their doctors will follow them very closely to find retinoblastoma at the earliest possible stage, if it occurs. It is very helpful to be able to tell which children have inherited the mutation that leads to retinoblastoma, since those children will need to be monitored closely.

Sometimes it is not possible to tell with certainty if a child inherited the RB1 gene mutation. In those cases the safest plan is to monitor children in the family closely for retinoblastoma with frequent eye exams.

Long-term effects of cancer treatment for retinoblastoma

With major advances in treatment in recent decades, many children treated for retinoblastoma are now surviving into adulthood. Doctors have learned that the treatment may affect children's health later in life, so watching for health effects as they get older has become more of a concern in recent years.

Just as the treatment of childhood cancer requires a very specialized approach, so does the care and follow-up after treatment. The earlier any problems can be recognized, the more likely it is they can be treated effectively.

Young people with cancer are at risk, to some degree, for several possible late effects of their cancer treatment. The risk of late effects depends on a number of factors, such as the specific treatments the child received, the doses of treatment, and the age of the child when being treated. These late effects may include:

Reduced kidney function

Heart problems after receiving certain chemotherapy drugs

Slowed or decreased growth and development

Changes in sexual development and ability to have children

Development of other cancers.

To help increase awareness of late effects and improve follow-up care of childhood cancer survivors throughout their lives, the Children’s Oncology Group (COG) has developed long-term follow-up guidelines for survivors of childhood cancers. These guidelines can help you know what to watch for, what type of screening tests should be done to look for problems, and how late effects may be treated.

Second cancers

Survivors of the hereditary form of retinoblastoma have a much higher risk for developing other types of cancer throughout their lives. This is because each cell in the body has an abnormal RB1 tumor suppressor gene, which would normally help stop some of these cancers from forming. Most of these cancers are very treatable if detected early, which is why it is very important that these children are followed closely throughout life. The entire body must be carefully examined to avoid missing these second cancers.

The most common secondary cancers among retinoblastoma survivors include:

Osteosarcoma (a type of bone cancer)

Soft tissue sarcomas (cancers that develop in muscle, tendons and ligaments, and fatty tissue)

Melanoma (a type of skin cancer)

Brain tumors

Lung cancer

Lymphoma

Breast cancer

The risk for these cancers is even higher if any of these parts of the body received radiation during treatment for retinoblastoma. Younger children treated with radiation therapy are more likely than older children to develop side effects such as second cancers or problems with bone growth in the irradiated area. Chemotherapy with certain drugs can also increase the risk of some cancers.

Because of the increased risk these children face, it's important that they're taught about other factors that might increase their risk of cancer as they get older. For example, sun exposure will increase the melanoma risk even further, and smoking will increase lung cancer risk. Of course, these children are also at increased risk of other cancers as they get older, just like children who did not have retinoblastoma.

Children with hereditary retinoblastoma also have a small risk of developing a tumor in the pineal gland within a few years. (This is known as trilateral retinoblastoma.) The pineal gland is a bean-sized structure lying under the middle of the brain. It can have cells similar to retina cells, which is why tumors can start there. This is why doctors often recommend that MRI scans be done regularly for up to 5 years to try to detect such tumors as early as possible.

What`s new in retinoblastoma research and treatment?

Research on retinoblastoma is being done at many medical centers, university hospitals, and other institutions around the world.

Genetics, genetic counseling, and gene therapy

The defective gene responsible for retinoblastoma (the RB1 gene) was identified in 1986. This discovery, together with technical advances in analyzing DNA changes, has made genetic testing a possibility.

A great deal of research has gone into figuring out how certain DNA changes in retinal cells cause them to become cancerous. Scientists understand these changes better for retinoblastoma than for most other cancer types. Although probably still years away, researchers hope that this understanding will one day lead to gene therapies, very specific treatments that can repair or counteract these DNA changes.

For example, researchers have recently identified an oncogene known as SYK that is overactive in retinoblastoma cells. Drugs that target the protein this gene makes are now being developed. Another gene called MDM4 also seems to be involved in the development of retinoblastoma, and drugs aimed at blocking its effects are being studied.

Treatment

Research is continuing the progress made in treating retinoblastoma over the past few decades.

Radiation therapy

External radiation therapy can effectively treat retinoblastoma, but it can cause side effects because the radiation often reaches nearby tissues as well. This limits its usefulness. Newer forms of radiation therapy such as intensity modulated radiation therapy (IMRT) and proton beam therapy are better able to target the tumor yet spare nearby tissues. These techniques, which are described in the section “Radiation therapy for retinoblastoma,” may help doctors limit the side effects from radiation therapy.

Other local treatments

Doctors continue to improve the instruments used for cryotherapy, laser therapy, and other local treatments. The goal is to more precisely kill tumor cells while sparing other parts of the eye.

Chemotherapy

Chemotherapy has played a more prominent role in treating many retinoblastomas in recent years.

Systemic chemotherapy

Chemotherapy given into a vein (IV) is now commonly used to shrink tumors before local treatments such as cryotherapy or laser therapy. Doctors are now studying whether giving chemotherapy after local treatments (known as adjuvant chemotherapy) might help prevent the recurrence of retinoblastoma, especially outside the eye. Doctors are also studying the use of different chemotherapy drugs such as topotecan, as well as new ways of combining current drugs, to try to improve the effectiveness of chemotherapy.

Localized chemotherapy

Chemotherapy can help shrink most retinoblastomas, but when it is given into the bloodstream it can cause side effects in different parts of the body. This limits the doses that can be given. Newer techniques may help keep the chemotherapy concentrated in the areas around the tumors. This may help doctors get higher doses of chemotherapy to the tumors while reducing some of these side effects.

Subtenon (subconjunctival or periocular) chemotherapy: Doctors are studying injecting the chemotherapy into the areas around the diseased eye. This might allow higher doses of chemotherapy to reach the tumor while limiting side effects elsewhere. There has been some success, but many doctors still consider this to be an experimental approach. New methods for periocular delivery are being studied, including placing small reservoirs loaded with chemotherapy outside the eye, which would release the drug into the eye for prolonged periods. If it proves to be useful, it will most likely be combined with other treatments (including systemic chemotherapy).

Intra-arterial chemotherapy: Another new approach is to inject chemotherapy directly into the ophthalmic artery, the main artery feeding the eye, using a long, thin catheter . When intra-arterial chemotherapy is used, the dose of the chemo drug is much lower than when is given by vein (less than 10% of the systemic dose), and the side effects related to the chemotherapy are minimal.

Early results with this technique in eyes with advanced tumors have been promising, with good tumor control and few side effects in most cases. In most cases it has allowed doctors to save an eye that otherwise would have needed to be removed. Some doctors are already using this new approach, although further study is needed to be sure it is safe and effective.

Intravitreal chemotherapy: Some doctors are studying injecting chemotherapy directly into fluid inside the eyeball (the vitreous) to treat tumors that are widespread within the eye and not helped by other treatments. The main concern with this technique is that placing the needle into the eye to give the chemo might open a small hole that could allow tumor cells to spread outside of the eye, so doctors are being very cautious with this approach. It is still in the very earliest stages of testing and is not commonly used.

High-dose chemotherapy and stem cell transplant

Retinoblastomas that have spread widely are much harder to treat than those still confined to the eye. The doses of chemotherapy that can be given are limited by the side effects they cause, especially in the bone marrow (where new blood cells are made). Researchers are now testing the value of giving very high-dose chemotherapy, followed by a stem cell transplant to replace the body’s bone marrow cells, which were killed by the chemotherapy. Several clinical trials are studying this approach.

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