Stages of Retinoblastoma, Part 2

by National Cancer Institute

(Page 3 of 3)

Radiation therapy

Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells. 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, stereotactic radiosurgery, and stereotaxic radiosurgery. This procedure does not involve surgery.

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.

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.

Photocoagulation

Photocoagulation is a procedure that uses laser light to destroy blood vessels to the tumor, causing the tumor cells to die. Photocoagulation may be used to treat small tumors. This is also called light coagulation.

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, or using ultrasound, microwaves, or infrared radiation (light that cannot be seen but can be felt as heat).

Chemotherapy

Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping the cells 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 spinal column, 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.

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

New types of treatment are being tested in clinical trials. These include the following:

Subtenon chemotherapy

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, photocoagulation, or thermotherapy).

High-dose chemotherapy with stem cell transplant

High-dose chemotherapy with stem cell transplant is a method 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.

This summary section refers to specific treatments under study in clinical trials, but it may not mention every new treatment being studied. Information about ongoing clinical trials is available from the NCI Web site.

Treatment Options for Retinoblastoma

Intraocular Retinoblastoma

If the cancer is in one eye and the tumor is large, treatment is usually enucleation.

If the cancer is in one eye and it is expected that vision can be saved, treatment may include the following:

• Radiation therapy.
• Photocoagulation.
• Cryotherapy.
• Thermotherapy.
• Chemotherapy (chemoreduction).

If the cancer is in both eyes, treatment may include the following:

• Enucleation of the eye with the most cancer, and radiation therapy to the other eye.
• Radiation therapy to both eyes or chemotherapy (chemoreduction) followed by local treatment. This may be done if there is a chance to save vision in both eyes.
• Surgery only, when vision cannot be saved.
• A clinical trial of subtenon chemotherapy combined with systemic chemotherapy and local treatment.

Extraocular Retinoblastoma

There is no standard treatment for extraocular retinoblastoma. Radiation therapy and chemotherapy have been used. Treatment may be a clinical trial of high-dose chemotherapy with stem cell transplant. Information about ongoing 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 (enucleation, radiation therapy, cryotherapy, photocoagulation, or thermotherapy).

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

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