Radiation Therapy for Neuroblastoma

Radiation therapy uses high-energy rays or particles to break DNA inside cells. These breaks keep cancer cells from growing and dividing and cause them to die.

When might radiation therapy be used?

Radiation therapy is sometimes a necessary part of treatment, but because of the possible long-term side effects in young children, doctors avoid using it when possible.

Most children with neuroblastoma will not need radiation therapy. It is most commonly used in children with high-risk neuroblastoma, typically after a stem cell transplant.

It might also be used for children with low- and intermediate-risk neuroblastoma if a child has life-threatening symptoms and needs emergency treatment to shrink the tumor.

How is radiation therapy given?

Two types of radiation therapy can be used to treat children with neuroblastoma:

• External beam radiation therapy
• MIBG radiotherapy

External beam radiation therapy

External radiation therapy uses a machine to focus a beam of radiation on the cancer. This type of treatment might be used:

• To try to shrink tumors before surgery, making them easier to remove
• To treat larger tumors that are causing serious problems (such as trouble breathing) and do not respond quickly to chemotherapy
• As part of the treatment regimen after a stem cell transplant in children with high-risk neuroblastoma to destroy neuroblastoma cells that remain behind. Radiation might be given to the primary tumor area and other areas of the body that might have active disease seen on an MIBG scan
• To help relieve pain caused by advanced neuroblastoma

Before the radiation treatments start, the radiation team will take 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.

Your child might also be fitted with a plastic mold resembling a body cast to keep them in the same position during each treatment so that the radiation can be aimed more accurately.

For each treatment session, your child lies on a special table while a machine delivers the radiation from a precise angle. Radiation therapy is like getting an x-ray, but the dose of radiation is much higher. The treatment is not painful. Each actual treatment lasts only a few minutes, but the setup time—getting your child into place for treatment—usually takes longer. Young children may be given medicine to make them sleep so they will not move during the treatment.

The number of radiation treatments given depends on the situation.

Possible side effects

Radiation therapy is sometimes an important part of treatment, but young children are sensitive to it, so doctors use as little radiation as possible to avoid or limit any problems. Radiation can cause both short-term and long-term side effects, which depend on the dose of radiation and where it is aimed. Short-term effects of radiation occur during or shortly after treatment. Long-term effects can take months or years to develop.

Close follow-up with doctors is important as children grow older so that any problems can be found and treated as soon as possible. For more on the possible long-term effects of treatment, see After Neuroblastoma Treatment.

MIBG radiotherapy

As described in Tests for Neuroblastoma, MIBG is a chemical similar to norepinephrine, which is made by sympathetic nerve cells. A slightly radioactive form of MIBG is sometimes injected into the blood as part of an imaging test to look for neuroblastoma cells in the body. This is called an MIBG scan.

A more highly radioactive form of MIBG can also be used to treat some children with advanced neuroblastoma, often along with other treatments. Once injected into the bloodstream, the MIBG goes to neuroblastoma cells anywhere in the body and delivers its radiation. This type of radiation travels only a very short distance, so it does not affect most healthy cells in the body.

A child treated with MIBG will need to stay in a special hospital room for a few days after the injection until most of the radiation has left the body. Most of the radiation leaves the body in the urine, so younger children might need to have a urinary catheter, usually for a couple of days.

Possible side effects

Common side effects of MIBG therapy during and shortly after treatment can include low blood counts, nausea, vomiting, low appetite, and tiredness.

Some children might have swollen cheeks from the MIBG treatment because it can affect the salivary glands.

MIBG can also cause high blood pressure for a short period of time.

Late effects of treatment with MIBG include low thyroid (hypothyroidism), thyroid nodules or thyroid cancer.