Radiation For Glioma: How To Choose Between Proton And Photon Therapy

“Usually, the way I can tell one way is better than the other is I do a radiation plan for proton therapy and the photon therapy,” Dr. Prashant Vempati, a radiation oncologist at UH Seidman Cancer Center in Cleveland, Ohio, tells SurvivorNet. “I look at how much collateral radiation is going to the normal structures of the brain that I care about — and one is usually better than the other.”

What is Proton Therapy?

Proton therapy is a highly precise form of radiation treatment that uses protons—high-energy hydrogen particles—to target and destroy cancer cells. Unlike traditional photon therapy, which uses high-energy X-rays to penetrate through the body, proton therapy has a distinct advantage: it delivers radiation to a specific depth in the body, stopping at the tumor.

“If the cancer is well lateralized, so if it’s on one side of the brain or one area of the brain that’s away from some of the critical structures, I usually do prefer proton therapy in those patients,” Vempati explains.

This unique property is known as the Bragg Peak, where the highest dose of energy is deposited directly in the tumor, with minimal radiation exposure to surrounding healthy tissues. As a result, proton therapy significantly reduces potential side effects and long-term complications associated with radiation treatment, but it’s not an option for all patients.

Proton therapy in glioma is not done in the vast majority of adults. While some radiation oncologists may advocate for this, it is not the standard of care based on national guidelines and the academic consensus. A distinction should be made between adults and children in pediatrics, there is more rationale to support the use of proton therapy.

Proton Therapy vs. Conventional Photon Therapy

“Imagine you have a critical structure in the brain that you want to protect, but the tumor is located nearby. With photon therapy, radiation passes through the tumor and continues traveling through the body, affecting healthy tissues along the way. With proton therapy, I can target the tumor precisely, delivering radiation only where it is needed while giving zero radiation to that critical structure,” Dr. Vempati says.

“There is an entrance dose but no exit dose, which means significantly fewer side effects and better protection for healthy tissues.”

This difference is crucial, especially for cancers in sensitive areas like the brain, spine, and vital organs, where avoiding unnecessary radiation exposure can improve quality of life and long-term health outcomes.

“If the cancer is more mid-line, closer to the center of the brain, that’s where proton therapy’s benefits don’t matter as much because it has to travel through a lot of the brain to get to that area,” Dr. Vempati notes.

In an adult population, proton therapy is not as supported and available in a limited number of sites nationally given a tremendous cost of the equipment.  As a result it is used rarely in brain tumor patients.

What are the Benefits of Proton Therapy?

There are several benefits to using this precise type of radiation, including:

• Greater Precision: Targets the tumor with high accuracy, sparing healthy tissues
• Reduced Side Effects: Less damage to surrounding organs means fewer complications
• Better Quality of Life: Patients often experience milder side effects, allowing them to continue daily activities with minimal disruption.
• Lower Risk of Secondary Cancers: Because proton therapy minimizes radiation exposure to healthy tissues, it reduces the likelihood of developing radiation-induced cancers later in life.
• Ideal for Pediatric Patients: Children are particularly vulnerable to radiation-related side effects, making proton therapy a better option for treating childhood cancers.
• Adult population: Proton therapy is not as supported and available in a limited number of sites nationally given a tremendous cost of the equipment.  As a result it is used rarely in brain tumor patients.

What is the Treatment Experience Like?

Patients undergoing proton therapy typically have a non-invasive, outpatient procedure that does not require hospitalization.

Here’s what to expect:

• Consultation and Planning: Your care team will conduct imaging scans (CT or MRI) to create a personalized treatment plan.
• Treatment Sessions: Proton therapy is usually delivered five days a week over the course of several weeks. Each session lasts about 30 minutes, but the actual proton beam delivery takes only a few minutes.
• Minimal Downtime: Most patients can resume normal activities shortly after treatment with mild side effects, such as fatigue or skin irritation, which gradually resolve.

Where Can I Get Proton Therapy?

Proton therapy centers are becoming more widely available, but they are still specialized facilities. Many major cancer centers and academic hospitals now offer proton therapy as part of their radiation oncology services.

To find a center near you, consider National Cancer Institute (NCI) designated centers, university-affiliated cancer hospitals, and specialized proton therapy centers.

Your oncologist can help you find the best location based on your diagnosis and treatment needs.

Is Proton Therapy Covered by Insurance?

Many insurance providers cover proton therapy, especially for cancers where its benefits are well-documented. Coverage may depend on:

• The type of cancer being treated
• Medical necessity as determined by your doctor
• Your specific insurance policy

It’s best to check with your insurance provider and discuss financial assistance programs that may be available through your treatment center.

Questions to Ask Your Doctor

• Can we review the risks vs. benefits of proton and photon therapy?
• What sort of radiation do people with my condition typically get?
• Is there anything I can do to prepare for radiation treatment?
• How will I be monitored after treatment?
• What side effects should I look out for?

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