Tipos de Cancer   /   Cánceres Pediátricos   /   Retinoblastoma   /   Recursos de NCI

NCI/PDQ^® Patients: Retinoblastoma Treatment (PDQ®)

National Cancer Institute
Ultima Vez Modificado: 19 de octubre del 2012

TABLE OF CONTENTS

• General Information About Retinoblastoma

• Stages of Retinoblastoma

• Recurrent Retinoblastoma

• Treatment Option Overview

• Treatment Options for Retinoblastoma
  • Intraocular Retinoblastoma
  • Extraocular Retinoblastoma
  • Recurrent Retinoblastoma

• To Learn More About Childhood Cancer

• Changes to This Summary (10/19/2012)

• Get More Information From NCI

• About PDQ®

General Information About Retinoblastoma

Retinoblastoma is a disease in which malignant (cancer) cells form in the tissues of the retina.

The retina is the nerve tissue that lines the inside of the back of the eye. The retina senses light and sends images to the brain by way of the optic nerve.Anatomy of the eye, showing the outside and inside of the eye including the sclera, cornea, iris, ciliary body, choroid, retina, vitreous humor, and optic nerve. The vitreous humor is a gel that fills the center of the eye.

Although retinoblastoma may occur at any age, it usually occurs in children younger than 5 years, most often younger than 2 years. The tumor may be in one eye or in both eyes. Retinoblastoma rarely spreads from the eye to nearby tissue or other parts of the body.

Retinoblastoma is sometimes caused by a gene mutation passed from the parent to the child.

Retinoblastoma is sometimes inherited (passed from the parent to the child). Retinoblastoma that is caused by an inherited gene mutation is called hereditary retinoblastoma. It usually occurs at a younger age than retinoblastoma that is not inherited. Retinoblastoma that occurs in only one eye is usually not inherited. Retinoblastoma that occurs in both eyes is thought to be inherited. Children who have a close family member with retinoblastoma should have regular eye exams. Early diagnosis of retinoblastoma may mean the child will need less intense treatment.

When hereditary retinoblastoma first occurs in only one eye, there is a chance it will develop later in the other eye. After diagnosis of retinoblastoma in one eye, regular follow-up exams of the healthy eye should be done every 2 to 4 months for at least 28 months. After treatment for retinoblastoma is finished, it is important that follow-up exams continue until the child is 5 years old.

Treatment for both types of retinoblastoma should include genetic counseling (a discussion with a trained professional about inherited diseases). The parents of a child with retinoblastoma should have an eye exam by an ophthalmologist (a doctor with special training in diseases of the eye) and genetic counseling about whether they should be tested for the gene that causes retinoblastoma and the risk of the child's brothers or sisters developing retinoblastoma. The child's brothers and sisters also should have regular eye exams by an ophthalmologist until age 5 years.

A child who has hereditary retinoblastoma is at risk for developing trilateral retinoblastoma and other cancers.

A child who has hereditary retinoblastoma is at risk for developing pineal tumors in the brain. This is called trilateral retinoblastoma and usually occurs more than 20 months after retinoblastoma is diagnosed. Regular screening using MRI (magnetic resonance imaging) every 6 months for 5 years may be recommended for a child with hereditary retinoblastoma or with retinoblastoma in one eye and a family history of the disease. CT scans (computerized tomography) should not be used for routine screening to avoid exposing the child to ionizing radiation. Hereditary retinoblastoma also increases the child's risk of developing other types of cancer such as bone or soft tissue sarcoma or melanoma in later years. Regular follow-up exams are important.

Possible signs of retinoblastoma include "white pupil" and eye pain or redness.

These and other symptoms may be caused by retinoblastoma. Other conditions may cause the same symptoms. Check with a doctor if your child has any of the following problems:

• Pupil of the eye appears white instead of red when light shines into it. This may be seen in flash photographs of the child.
• Eyes appear to be looking in different directions.
• Pain or redness in the eye.

Tests that examine the retina are used to detect (find) and diagnose retinoblastoma.

The following tests and procedures may be used:

• Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient's health habits and past illnesses and treatments will also be taken. The doctor will ask if there is a family history of retinoblastoma.
• Eye exam with dilated pupil: An exam of the eye in which the pupil is dilated (opened wider) with medicated eyedrops to allow the doctor to look through the lens and pupil to the retina. The inside of the eye, including the retina and the optic nerve, is examined with a light. Depending on the age of the child, this exam may be done under anesthesia.
• Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram.
• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the eye, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body, such as the eye. This procedure is also called nuclear magnetic resonance imaging (NMRI).

Retinoblastoma is usually diagnosed without a biopsy (removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer).

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) and treatment options depend on the following:

• The stage of the cancer.
• The age of the patient.
• How likely it is that vision can be saved in one or both eyes.
• The size and number of tumors.
• Whether the patient has glaucoma.
• Whether trilateral retinoblastoma occurs.

Stages of Retinoblastoma

After retinoblastoma has been diagnosed, tests are done to find out if cancer cells have spread within the eye or to other parts of the body.

The process used to find out if cancer has spread within the eye or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. The following tests and procedures may be used in the staging process:

• Eye exam with dilated pupil: An exam of the eye in which the pupil is dilated (opened wider) with medicated eyedrops to allow the doctor to look through the lens and pupil to the retina. The inside of the eye, including the retina and the optic nerve, is examined using a light. Depending on the age of the child, this exam may be done under anesthesia.
• Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram.
• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the eye, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body, such as the eye. This procedure is also called nuclear magnetic resonance imaging (NMRI).
• Lumbar puncture: A procedure used to collect cerebrospinal fluid from the spinal column. This is done by placing a needle into the spinal column. This procedure is also called an LP or spinal tap. A lumbar puncture may be done if tests show that the cancer may have spread out of the eye.
• Bone marrow aspiration and biopsy: The removal of bone marrow, blood, and a small piece of bone by inserting a hollow needle into the hipbone or breastbone. A pathologist views the bone marrow, blood, and bone under a microscope to look for signs of cancer.

There are several staging systems for retinoblastoma. For treatment, retinoblastoma is classified as intraocular (within the eye) or extraocular (outside the eye).

The following stages are used for retinoblastoma:

Intraocular retinoblastoma

In intraocular retinoblastoma, cancer is found in the eye and may be only in the retina or may also be in other parts of the eye such as the choroid, ciliary body, or part of the optic nerve. Cancer has not spread to tissues around the outside of the eye or to other parts of the body.

Extraocular retinoblastoma

In extraocular retinoblastoma, cancer has spread beyond the eye. It may be found in tissues around the eye (orbital retinoblastoma) or it may have spread to the central nervous system (brain and spinal cord) or to other parts of the body such as the bone marrow or lymph nodes (metastatic retinoblastoma).

There are three ways that cancer spreads in the body.

The three ways that cancer spreads in the body are:

• Through tissue. Cancer invades the surrounding normal tissue.
• Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
• Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

Recurrent Retinoblastoma

Recurrent retinoblastoma is cancer that has recurred (come back) after it has been treated. The cancer may recur in the eye, in tissues around the eye, or in other places in the body.

Treatment Option Overview

There are different types of treatment for patients with retinoblastoma.

Different types of treatment are available for patients with retinoblastoma. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment.

Because cancer in children is rare, taking part in a clinical trial should be considered. Some clinical trials are open only to patients who have not started treatment.

Children with retinoblastoma should have their treatment planned by a team of health care providers who are experts in treating cancer in children.

Treatment will be overseen by a pediatric oncologist, a doctor who specializes in treating children with cancer. The pediatric oncologist works with other health care providers who are experts in treating children with eye cancer and who specialize in certain areas of medicine. These may include a pediatric ophthalmologist (children's eye doctor) who has a lot of experience in treating retinoblastoma and the following specialists:

• Pediatric surgeon.
• Pediatric hematologist.
• Radiation oncologist.
• Neurologist.
• Pediatric nurse specialist.
• Rehabilitation specialist.
• Psychologist.
• Social workers.
• Geneticist.

Some cancer treatments cause side effects months or years after treatment has ended.

Side effects from cancer treatment that begin during or after treatment and continue for months or years are called late effects. Late effects of cancer treatment may include the following:

• Physical problems such as problems with seeing clearly.
• Changes in mood, feelings, thinking, learning, or memory.
• Second cancers (new types of cancer).

Some late effects may be treated or controlled. It is important to talk with your child's doctors about the effects cancer treatment can have on your child. (See the PDQ® summary on Late Effects of Treatment for Childhood Cancer for more information.)

Children with the inherited form of retinoblastoma have an increased risk of developing second cancers. Children, especially those younger than 12 years, who have been treated for retinoblastoma with radiation therapy have a risk of developing second cancers. Regular follow-up by health professionals who are expert in finding and treating late effects is important.

Five types of standard treatment are used:

Enucleation

Enucleation is surgery to remove the eye and part of the optic nerve. The eye will be checked with a microscope to see if there are any signs that the cancer is likely to spread to other parts of the body. This is done if the tumor is large and there is little or no chance that vision can be saved. The patient will be fitted for an artificial eye after this surgery. Close follow-up is needed for 2 years or more to check the other eye and to check for signs of recurrence in the area around the eye.

Radiation therapy

Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, plaques, or catheters that are placed directly into or near the cancer. The way the radiation therapy is given depends on the type and stage of the cancer being treated. Methods of radiation therapy used to treat retinoblastoma include the following:

• Intensity-modulated radiation therapy (IMRT): A type of 3-dimensional (3-D) radiation therapy that uses a computer to make pictures of the size and shape of the tumor. Thin beams of radiation of different intensities (strengths) are aimed at the tumor from many angles. This type of radiation therapy causes less damage to healthy tissue near the tumor.
• Stereotactic radiation therapy: Radiation therapy that uses a rigid head frame attached to the skull to aim high-dose radiation beams directly at the tumors, causing less damage to nearby healthy tissue. It is also called stereotactic external-beam radiation and stereotaxic radiation therapy.
• Proton beam radiation therapy: Radiation therapy that uses protons made by a special machine. A proton is a type of high-energy radiation that is different from an x-ray.
• Plaque radiotherapy: Radioactive seeds are attached to one side of a disk, called a plaque, and placed directly on the outside wall of the eye near the tumor. The side of the plaque with the seeds on it faces the eyeball, aiming radiation at the tumor. The plaque helps protect other nearby tissue from the radiation.Plaque radiotherapy of the eye. A type of radiation therapy used to treat eye tumors. Radioactive seeds are placed on one side of a thin piece of metal (usually gold) called a plaque. The plaque is sewn onto the outside wall of the eye. The seeds give off radiation which kills the cancer. The plaque is removed at the end of treatment, which usually lasts for several days.

Cryotherapy

Cryotherapy is a treatment that uses an instrument to freeze and destroy abnormal tissue, such as carcinoma in situ. This type of treatment is also called cryosurgery.

Thermotherapy

Thermotherapy is the use of heat to destroy cancer cells. Thermotherapy may be given using a laser beam aimed through the dilated pupil or onto the outside of the eyeball. Thermotherapy may be used alone for small tumors or combined with chemotherapy for larger tumors. This type of treatment is also called laser therapy.

Chemotherapy

Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the cerebrospinal fluid, an organ (such as the eye), or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). The way the chemotherapy is given depends on the type and stage of the cancer being treated.

Subtenon chemotherapy may also be used to treat some types of retinoblastoma. Subtenon chemotherapy is the use of drugs injected through the membrane covering the muscles and nerves at the back of the eyeball. This is a type of regional chemotherapy. It is usually combined with systemic chemotherapy and local treatment (such as radiation therapy, cryotherapy, or thermotherapy).

A form of chemotherapy called chemoreduction may be used to treat some types of retinoblastoma. Chemoreduction reduces the size of the tumor so it may be treated with local treatment (such as radiation therapy, cryotherapy, or thermotherapy).

See Drugs Approved for Retinoblastoma for more information.

New types of treatment are being tested in clinical trials.

This summary section describes treatments that are being studied in clinical trials. It may not mention every new treatment being studied. Information about clinical trials is available from the NCI Web site.

Ophthalmic arterial infusion therapy

Ophthalmic arterial infusion therapy is a type of regional chemotherapy used to deliver anticancer drugs directly to the eye. A catheter is put into an artery that leads to the eye and the anticancer drug is given through the catheter. During this treatment, a small balloon may be inserted into the artery to block it and keep most of the anticancer drug trapped near the tumor.

High-dose chemotherapy with stem cell rescue

High-dose chemotherapy with stem cell rescue is a way of giving high doses of chemotherapy and replacing blood-forming cells destroyed by the cancer treatment. Stem cells (immature blood cells) are removed from the blood or bone marrow of the patient or a donor and are frozen and stored. After the chemotherapy is completed, the stored stem cells are thawed and given back to the patient through an infusion. These reinfused stem cells grow into (and restore) the body's blood cells.

Patients may want to think about taking part in a clinical trial.

For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.

Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.

Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.

Patients can enter clinical trials before, during, or after starting their cancer treatment.

Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.

Clinical trials are taking place in many parts of the country. See the Treatment Options section that follows for links to current treatment clinical trials. These have been retrieved from NCI's listing of clinical trials.

Follow-up tests may be needed.

Some of the tests that were done to diagnose the cancer or to find out the stage of the cancer may be repeated. Some tests will be repeated in order to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests. This is sometimes called re-staging.

Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your child's condition has changed or if the cancer has recurred (come back). These tests are sometimes called follow-up tests or check-ups.

Treatment Options for Retinoblastoma

A link to a list of current clinical trials is included for each treatment section. For some types or stages of cancer, there may not be any trials listed. Check with your child's doctor for clinical trials that are not listed here but may be right for your child.

Intraocular Retinoblastoma

If the cancer is in one or both eyes and it is expected that vision can be saved, treatment may include one or more of the following:

• External-beam radiation therapy or plaque radiotherapy .
• Cryotherapy with or without chemotherapy.
• Thermotherapy.
• Chemotherapy (chemoreduction).
• A clinical trial of intensity-modulated radiation therapy, stereotactic radiotherapy, or proton beam radiation therapy.
• A clinical trial of ophthalmic arterial infusion therapy.

For large tumors in one or both eyes, treatment may include the following:

• Enucleation. Chemotherapy may be given to shrink the tumor before surgery or after surgery to lower the risk that the cancer will spread to other parts of the body.

Other treatments for cancer in both eyes include the following:

• Chemotherapy (chemoreduction) followed by local treatment such as cryotherapy, thermotherapy, or plaque radiotherapy. This may be done if there is a chance to save vision in both eyes.
• Subtenon chemotherapy combined with systemic chemotherapy and local treatment.
• A clinical trial of new combinations of chemotherapy and other treatments to the eye.

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with intraocular retinoblastoma. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug. General information about clinical trials is available from the NCI Web site.

Extraocular Retinoblastoma

There is no standard treatment for extraocular retinoblastoma. Treatment may include combinations of the following:

• Chemotherapy.
• Radiation therapy.
• Surgery.

For retinoblastoma that has spread to the area around the eye, treatment may be the following:

• Systemic chemotherapy followed by surgery (enucleation). More chemotherapy and radiation therapy may be given after surgery.

For retinoblastoma that has spread to the brain, treatment may be the following:

• Chemotherapy.
• Radiation therapy to the brain and spinal cord.

For trilateral retinoblastoma, treatment may include the following:

• Chemotherapy followed by high-dose chemotherapy and stem cell rescue.

For retinoblastoma that has spread to other parts of the body, treatment may be the following:

• High-dose chemotherapy and stem cell rescue.
• A clinical trial of chemotherapy followed by high-dose chemotherapy with stem cell rescue and/or radiation therapy.

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with extraocular retinoblastoma. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug. General information about clinical trials is available from the NCI Web site.

Recurrent Retinoblastoma

If the cancer is small and in the eye only, treatment is usually local therapy, which may include the following:

• Plaque radiotherapy.
• Cryotherapy.
• Thermotherapy.

If the cancer around the eye is large and the eye has been removed, treatment is usually the following:

• Chemotherapy followed by radiation therapy.

If the cancer comes back outside of the eye, treatment will depend on many things and may be within a clinical trial, which may be the following:

• Chemotherapy combined with high-dose chemotherapy and stem cell rescue with radiation therapy.

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with recurrent retinoblastoma. For more specific results, refine the search by using other search features, such as the location of the trial, the type of treatment, or the name of the drug. General information about clinical trials is available from the NCI Web site.

To Learn More About Childhood Cancer

For more information from the National Cancer Institute about the treatment of retinoblastoma, see the following:

• Retinoblastoma Home Page
• Drugs Approved for Retinoblastoma
• Biological Therapies for Cancer: Questions and Answers
• Gene Therapy for Cancer: Questions and Answers

For more childhood cancer information and other general cancer resources from the National Cancer Institute, see the following:

• What You Need to Know About Cancer
• Childhood Cancers
• CureSearch for Children's Cancer
• Late Effects of Treatment for Childhood Cancer
• Adolescents and Young Adults with Cancer
• Young People with Cancer: A Handbook for Parents
• Care for Children and Adolescents with Cancer
• Understanding Cancer Series: Cancer
• Cancer Staging
• Coping with Cancer: Supportive and Palliative Care
• Questions to Ask Your Doctor About Cancer
• Cancer Library
• Information for Survivors/Caregivers/Advocates

Changes to This Summary (10/19/2012)

The PDQ® cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

Changes were made to this summary to match those made to the health professional version and images were added.

Get More Information From NCI

Call 1-800-4-CANCER

For more information, U.S. residents may call the National Cancer Institute's (NCI's) Cancer Information Service toll-free at 1-800-4-CANCER (1-800-422-6237) Monday through Friday from 8:00 a.m. to 8:00 p.m., Eastern Time. A trained Cancer Information Specialist is available to answer your questions.

Chat online

The NCI's LiveHelp online chat service provides Internet users with the ability to chat online with an Information Specialist. The service is available from 8:00 a.m. to 11:00 p.m. Eastern time, Monday through Friday. Information Specialists can help Internet users find information on NCI Web sites and answer questions about cancer.

Write to us

For more information from the NCI, please write to this address:

• NCI Public Inquiries Office
• Suite 3036A
• 6116 Executive Boulevard, MSC8322
• Bethesda, MD 20892-8322

Search the NCI Web site

The NCI Web site provides online access to information on cancer, clinical trials, and other Web sites and organizations that offer support and resources for cancer patients and their families. For a quick search, use the search box in the upper right corner of each Web page. The results for a wide range of search terms will include a list of "Best Bets," editorially chosen Web pages that are most closely related to the search term entered.

There are also many other places to get materials and information about cancer treatment and services. Hospitals in your area may have information about local and regional agencies that have information on finances, getting to and from treatment, receiving care at home, and dealing with problems related to cancer treatment.

Find Publications

The NCI has booklets and other materials for patients, health professionals, and the public. These publications discuss types of cancer, methods of cancer treatment, coping with cancer, and clinical trials. Some publications provide information on tests for cancer, cancer causes and prevention, cancer statistics, and NCI research activities. NCI materials on these and other topics may be ordered online or printed directly from the NCI Publications Locator. These materials can also be ordered by telephone from the Cancer Information Service toll-free at 1-800-4-CANCER (1-800-422-6237).

About PDQ®

PDQ® is a comprehensive cancer database available on NCI's Web site.

PDQ® is the National Cancer Institute's (NCI's) comprehensive cancer information database. Most of the information contained in PDQ® is available online at NCI's Web site. PDQ® is provided as a service of the NCI. The NCI is part of the National Institutes of Health, the federal government's focal point for biomedical research.

PDQ® contains cancer information summaries.

The PDQ® database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries are available in two versions. The health professional versions provide detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions provide current and accurate cancer information.

Images in the PDQ® summaries are used with permission of the author(s), artist, and/or publisher for use within the PDQ® summaries only. Permission to use images outside the context of PDQ® information must be obtained from the owner(s) and cannot be granted by the National Cancer Institute. Information about using the illustrations in the PDQ® summaries, along with many other cancer-related images, are available in Visuals Online, a collection of over 2,000 scientific images.

The PDQ® cancer information summaries are developed by cancer experts and reviewed regularly.

Editorial Boards made up of experts in oncology and related specialties are responsible for writing and maintaining the cancer information summaries. The summaries are reviewed regularly and changes are made as new information becomes available. The date on each summary ("Date Last Modified") indicates the time of the most recent change.

PDQ® also contains information on clinical trials.

A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." In the United States, about two-thirds of children with cancer are treated in a clinical trial at some point in their illness.

Listings of clinical trials are included in PDQ® and are available online at NCI's Web site. Descriptions of the trials are available in health professional and patient versions. For additional help in locating a childhood cancer clinical trial, call the Cancer Information Service at 1-800-4-CANCER (1-800-422-6237).

The PDQ® database contains listings of groups specializing in clinical trials.

The Children's Oncology Group (COG) is the major group that organizes clinical trials for childhood cancers in the United States. Information about contacting COG is available on the NCI Web site or from the Cancer Information Service at 1-800-4-CANCER (1-800-422-6237).