Radiation Therapy For Gliomas: The Debate On Delayed Treatment

“Even if we’re talking about radiotherapy in a postoperative setting, letting discretion be the better part of valor, letting those postoperative changes evolve, letting that cavity collapse so that we are effectively treating a smaller target when we are individualizing radiotherapy plan. That’s been part of this conversation for a long time,” says Dr. Raleigh.

He explains that although there’s debate over when to start radiation after glioma surgery, history shows that patients who survive cancer long-term often benefit from starting aggressive treatments early. He also notes that in the past, some treatments were too extreme and sometimes didn’t work, but over time, the trend has shifted toward starting treatment earlier and being more aggressive. He suggests that early, strong treatment tends to lead to better results, even though the approach has changed over time.

Dr. Raleigh notes that the “heart” of this debate is when is the best time to start treatment. And does our refined understanding of the biology of this and other cancers, does that move the goalposts for a win soon enough might be enough? I think these are very nuanced questions.

“Yes, it leads to nuanced, often impassioned discussions at the tumor board where we’re trying to piece all this together. These are good problems to have.”

Radiation Therapy for Gliomas What to Expect Before, During, and After Treatment

Meanwhile, Dr. Erik Sulman, head of radiation oncology at Duke University School of Medicine, has also offered his perspective on the matter, when it comes to the timing of radiation, chemotherapy, and newer therapies like IDH inhibitors.

Dr. Sulman tells us, “The focus isn’t really ‘can we delay radiation’ or ‘can we delay chemotherapy,’ because that isn’t necessarily an end. The focus is can we just overall improve the quality and duration of survival for the patient? And so it may be that using an IDH inhibitor adds at a certain time in treatment, maybe in the beginning, it adds years to that survival.”

RELATED: IDH Inhibitors — A New Treatment Option for Low Grade Gliomas

Referring to how clinical trials help shape glioma treatment plans, he continued, “The trials that we’ll do to kind of address that are again, not really about delaying a toxicity that may or may not be as relevant today with modern therapy, but just finding the right sequence of things to really maximize that overall time.

“The challenge is the trials that we’ve done so far for these diagnoses other than the INDIGO trial you heard about have taken decades. They started in the nineties and were reported in the mid-2000s. And so how do you do a trial? And there’s practical challenges to doing that. If we started the trial today, those of us sitting up here, our children would be the ones reporting the result.”

It’s important to note that the INDIGO Trial referred to by Dr. Sulman, represents a significant advancement in glioma research and treatment. Patients treated with Vorasidenib experienced a notable increase in progression-free survival, showcasing the drug’s ability to effectively control tumor growth. This is especially beneficial for individuals with low-grade gliomas, as postponing the need for aggressive treatments like chemotherapy or radiation can have a profound positive impact on their overall quality of life.

Although these treatments are effective, they often come with severe side effects like cognitive difficulties, fatigue, and long-term health problems. Thus, by postponing the need for such therapies, a patient’s quality of life may be improved.”

Dr. Sulman then stressed that the timing of these trials is the “real challenge,” adding, “There’s a patent life on a drug, and so if you’re waiting 15 or 20 years to get a result, understandably, that’s a hard thing to invest in. And it is probably beyond the capacity of our healthcare system to fund that kind of a trial that long.

“So we don’t have the answers, but I think it’s important to recognize those goals.”

The development of IDH inhibitors has sparked a surge in investment and progress in brain tumor research, treatments, and drug development, Dr. Surman says. He remains optimistic about breakthroughs like radioligand therapies and flash radiotherapy, which could significantly reduce treatment toxicity. However, he stresses the importance of ensuring these emerging therapies are accessible to all patients.

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Dr. Raleigh also points out that much of the detailed data obtained on radiotherapy toxicities over the years stem from older treatment methods.

“It’s only because of the really hard fought work from a lot of cooperative groups that we have such granular data about those toxicities. But as radiotherapy modalities change and evolve, whether it’s flash or radionuclide therapies that we’re seeing, I think these things need to be revisited in the context of our evolving biologic standings. I think the importance of that really can’t be overstated.”

Understanding Radiation Therapy in the Treatment of Glioma

Whether radiation is necessary depends on the type of glioma diagnosed. Low-grade gliomas, such as grade 1 and grade 2, might not require radiation at all. However, high-grade gliomas, including grade 3 and grade 4, typically require radiation therapy either immediately following surgery or soon after diagnosis.

“Radiation therapy is where we can target radiation to kill the cancer cells selectively — for that, we need to be really precise,” Dr. Prashant Vempati, a radiation oncologist at UH Seidman Cancer Center in Cleveland, Ohio, explains to SurvivorNet.

Your medical team will evaluate your specific situation to decide if radiation therapy is the most appropriate treatment option for you.

Radiation therapy utilizes high-energy waves or particles to damage the DNA of cells that eventually leads to cancer cell death. Clinical trials have demonstrated that radiation therapy can slow tumor progression and improve outcomes for patients with high-grade gliomas. By focusing on specific areas, radiation therapy aims to maximize tumor cell destruction while minimizing damage to surrounding healthy tissue.

The Preparation Process

• The Simulation Scan: Before starting treatment, you will undergo a simulation scan, which typically involves a CT scan of your brain. During this process, an immobilization device is used to keep you still during treatment. This device is usually a moldable plastic mask that resembles a net, allowing you to see and breathe through it comfortably. The purpose of this step is to ensure precision in targeting the treatment area.
• Contouring: After your simulation scan, your doctor will use the images obtained, along with MRI scans of your brain, to outline the exact area that requires treatment. This process, known as contouring, helps the medical team define the radiation target while avoiding critical structures such as your eyes, lenses, and brainstem. By carefully mapping out the treatment area, your doctor ensures that the radiation dose is delivered as effectively and safely as possible.
• Planning: A specialized expert called a dosimetrist will then take the information from your scans and work alongside your doctor to create a detailed radiation plan. The dosimetrist is highly trained in radiation delivery methods and will design a customized plan that optimizes treatment effectiveness while minimizing side effects.
• Quality Assurance: Once your doctor has approved the radiation plan, it is sent to a radiation physicist for verification. The physicist ensures that the treatment plan can be safely and accurately delivered to you. This critical step guarantees that the radiation dose is appropriate and that the technology used is functioning optimally.
• Verification: Before your first treatment session, you will return to the clinic for a verification step. A radiation therapist, a professional trained to administer radiation therapy, will take X-rays to confirm that your positioning matches the setup from your simulation scan. This ensures that the radiation is delivered precisely as planned.

There are several different ways to deliver radiation therapy, depending on the specifics of your glioma and your overall treatment plan. Common methods include:

• External Beam Radiation Therapy (EBRT): This is the most commonly used type of radiation therapy. A machine called a linear accelerator (LINAC) delivers high-energy beams (like X-rays) to your tumor from outside the body. The treatment is painless and typically lasts a few minutes per session. A technique called
• Volumetric Modulated Arc Therapy (VMAT): A method to deliver radiation therapy faster than conventional techniques and allows for increased precision, therefore reducing exposure to surrounding healthy tissues.
• Proton Therapy: A newer form of radiation therapy, proton therapy uses proton beams instead of X-rays to target tumors. This method allows for more precise radiation delivery and can reduce damage to surrounding healthy tissues, potentially leading to fewer side effects.

Your doctor will discuss the best radiation delivery method for your case based on your tumor’s characteristics and your overall health.

What Patients Need to Know About Monitoring & Glioma Recurrence

Questions To Ask Your Doctor Amid Glioma Treatment

• What are my treatment options? Will I be undergoing surgery, radiation therapy, chemotherapy, or clinical trials?
• How will each of these options affect my prognosis?
• What are the potential side effects of the treatment?
• How will we monitor my progress during and after treatment?
• Are there any clinical trials or experimental treatments available for me?

Contributing: SurvivorNet Staff

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