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Evolving Therapies for pLGG Eliminate Need for Radiation
Key Takeaways
Advancements in surgery and chemotherapy have significantly reduced the need for radiation therapy to treat pediatric low-grade glioma (pLGG).
Avoiding radiation minimizes long-term cognitive, endocrine and tumor-related risks in survivors of pLGG.
Peter de Blank, MD, MSCE, is now leading a study to determine whether targeted chemotherapy will continue to improve quality of life for patients with pLGG, as compared to traditional chemotherapy.
Radiation works very well and stops gliomas from growing most of the time. The problem is that it has multiple side effects associated with it that don’t always come out immediately.
Peter de Blank, MD, MSCE
Reserving radiation for pediatric low-grade glioma (pLGG) with no other options improves late outcomes for survivors. That’s according to a recently published study led by corresponding author Peter de Blank, MD, MSCE, co-medical director at The Cure Starts Now Foundation Brain Tumor Center at Cincinnati Children’s.
The study, published in the journal Nature Cancer, found that successful outcomes from evolving surgical and chemotherapy treatments for pLGG have greatly reduced the need for radiation therapy.
“Radiation works very well and stops gliomas from growing most of the time,” de Blank says. “The problem is that it has multiple side effects associated with it that don’t always come out immediately.”
Late Effects Reduced in Adult Survivors of Childhood Gliomas
Pediatric low-grade glioma is the most common brain tumor in children, accounting for about one-third of all brain tumors diagnosed each year in the United States. Because pLGG has an excellent survival rate, choosing how to treat it requires careful consideration to minimize late toxicity.
While effective against low-grade glioma itself, radiation therapy can cause long-term deficits in cognition and endocrine function and can sometimes cause new tumors that are even harder to treat. de Blank and his team wanted to see if therapy that’s evolved to delay or eliminate radiation for low-grade tumors has affected late mortality and morbidity in adult survivors of the disease.
The study followed 2,501 adult survivors of pLGG, who were diagnosed in the 1970s, 1980s and 1990s, for an average of 24 years. From the 1970s to the 1990s, the proportion of survivors exposed to cranial radiation decreased from 62.6% to 26.0%, while the proportion of survivors exposed to surgery alone or surgery with chemotherapy increased.
Over the three decades, the risk of late mortality, chronic health conditions and subsequent neoplasms among survivors decreased. Yet when researchers included treatment in the model, the effect of time decreased, which shows that some of the improvements in outcomes for pLGG over time are a result of changes in how patients are treated.
Moving away from radiation and toward chemotherapy and surgery is responsible for many of the improvements in late outcomes over time, de Blank says. Other reasons for this improvement include better screening and survivorship care, the advent of MRI, and improvements in radiation and surgical techniques. More recent advances, like proton radiation therapy that reduces the amount of healthy brain tissue exposed to radiation, were too new to be included in the study but are expected to decrease the toxicity of radiation.
Future Research Will Focus on How to Further Improve Outcomes
Avoiding radiation when it’s not needed improves outcomes, but delayed radiation was not associated with better outcomes or fewer reports of impaired learning or concentration. de Blank says it may be that a longer delay is needed to see important effects, or that the key is to avoid radiation altogether whenever possible.
“We looked at whether delays in radiation improved late outcomes,” he says. “Over the same three decades, the proportion of survivors who received delayed radiation (a year or more from diagnosis) increased from 3.2% to 30.1%, suggesting that treating physicians were trying to delay radiation when possible.”
New targeted chemotherapy [may] further improve outcomes and quality of life for pLGG patients compared to traditional chemotherapy.
