Radiation Therapy for Ependymoma

Ependymomas are uncommon tumors that can occur in the brain or spine and affect individuals of any age. The primary treatment options for these tumors are surgery and radiation therapy, which are often used together to achieve the best possible outcome.

Although radiation therapy can be effective in preventing tumor regrowth, concerns about radiation exposure, particularly in children, may be a cause for anxiety among parents and caregivers. In this article, we will focus on the use of radiation therapy for ependymomas and provide an overview of the potential risks, benefits, and logistics associated with this treatment option.

Complete surgical removal is currently the most effective treatment for brain and spinal ependymomas. Radiation therapy may also be recommended following surgery, particularly if the tumor is more aggressive or if significant pieces of the tumor remain. After treatment, imaging tests such as MRIs or procedures such as lumbar punctures may be necessary to monitor the tumor for regrowth and spread.

Treatment plans for ependymoma vary depending on the patient's age, tumor location, and tumor grade. Although chemotherapy has a limited role in treating ependymoma, it may be considered for young children under 18 months of age or patients who have exhausted all other treatment options.

There are various types of radiation systems and techniques. Conformal radiation therapy techniques are commonly used for the treatment of ependymoma, but the specific approach and regimen will depend on your individual case. Radiation therapy is typically delivered in 20- to 30-minute sessions, or fractions, over the course of 4 to 8 weeks. Below are several types of radiation systems:

Conventional (2D) radiation therapy: This older technique uses square or rectangular targets for radiation treatment. Because tumors have more complex shapes, healthy tissues within the target box are also affected. These techniques are now rarely used.

Conformal (3D) radiation therapy: This newer technique uses advanced planning to shape the radiation beam in 3D space. This allows for the radiation beams to tightly conform to the tumor boundaries and avoid healthy tissues.

Intensity-modulated radiation therapy (IMRT): This is a type of conformal radiation therapy that allows for the beam's intensity to be modified within the 3D target. This enables even greater customization of the radiation beam, allowing for higher intensities to be delivered to the denser areas of the tumor.

Stereotactic radiosurgery: This technique uses focused high-energy beams to precisely target the tumor and can be delivered through several systems such as the Gamma Knife or CyberKnife. Treatment is usually administered in a single longer session and may be repeated several times.

The type of particle used in the radiation beam can have implications on treatment. Here are some common types of particles used in radiation therapy:

• Photons (e.g., x-rays, gamma rays): Photons are the basic unit of electromagnetic radiation, which includes X-rays and gamma rays. Most machines use photon beams. However, as photons travel through tissues to the target tumor, they scatter small amounts of radiation along the path into healthy tissues.
• Protons: Protons are positively charged particles found in the nucleus of atoms. Proton beams have the unique advantage of depositing most of their energy at the target site, minimizing damage to surrounding healthy tissues. However, proton therapy must be administered at specialized centers and may not be easily accessible.
• Electrons: Electrons are negatively charged particles that orbit the nucleus of atoms. Electron beams do not travel very far and are typically limited to treating superficial tumors on the skin.

Ependymoma radiotherapy is usually administered daily from Monday through Friday for a duration of 4 to 8 weeks. Although the actual delivery of radiation may take only a few minutes, the session can last up to 15 to 30 minutes as the medical team carefully plans the radiation dosage using a computer to precisely target the tumor. Your physician will schedule regular follow-up appointments to monitor for any adverse effects and changes in tumor size.  

One of the main benefits of radiation therapy for ependymomas is that it can help to reduce the risk of tumor regrowth or recurrence. Radiation therapy may be used in combination with surgery, particularly for more aggressive ependymomas. However, for low-grade ependymomas, the decision to use radiation therapy must consider the risks and potential side effects of treatment.

Possible side effects of radiation therapy include:

• Skin changes, swelling, flaking, or redness
• Nausea
• Dry mouth
• Irritation and redness in the mouth
• Hair loss
• Fatigue
• Difficulty in swallowing
• Loss of taste or change in taste

Most of these side effects are manageable with standard medical approaches. However, radiation therapy, especially for young children, may cause long-term neurological and cognitive problems. These deficits may not be observed until more than a decade after radiation therapy treatment and may involve the following domains:

• Attention: This is the ability to focus and can manifest as difficulties with:
  • Paying attention during conversations
  • Completing tasks requiring sustained focus
  • Time management
• Executive functioning: This is related to problem-solving skills and decision-making, as well as the ability to plan, organize, initiate, and complete tasks. Deficits in executive functioning may manifest as difficulties with:
  • Breaking down complex assignments into manageable steps
  • Initiating tasks or starting new projects
  • Remembering information over short periods
• Information processing speed: This refers to the rate at which a person can process and interpret incoming information. Deficits can manifest as difficulties with:
  • Processing and responding to information quickly
  • Reading, writing, and complex problem solving
  • Keeping up with conversations or timed tests or assignments

Not all children who undergo radiation therapy will develop cognitive deficits, but it is a potential risk that should be considered when deciding on a treatment plan. In many cases, the benefits of radiation therapy in preventing tumor recurrence outweigh the potential risks. 

After being treated for ependymoma, it is important to have regular follow-up appointments with your medical team. The timing and frequency of these appointments will depend on the specifics of your treatment plan and should be discussed with your physician. Imaging studies may be scheduled at specific intervals to monitor for any signs of recurrence.

If a recurrence does occur or if all treatment options have been exhausted, participation in clinical trials may be considered. Support groups can also be helpful for patients and their families to cope with the emotional and practical challenges of living with ependymoma. These groups can provide a safe space to connect with others who understand the experience and offer resources and support.

• Radiation therapy is a commonly used treatment option for ependymoma to prevent tumor regrowth.
• Treatment usually involves daily fractions of radiation delivered over 4 to 8 weeks.
• Although most side effects are manageable with standard medical approaches, radiation exposure in young children may cause long-term issues with thinking and behavior.

• Collaborative Ependymoma Research Network (CERN)
• American Brain Tumor Association (ABTA): Ependymoma
• The Childhood Brain Tumor Foundation 
• Pediatric Brain Tumor Foundation