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Low-grade gliomas represent an uncommon but important class of primary brain tumors, especially because of long survivorship.
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Radiotherapy is one of the main components of treatment for patients with low-grade glioma and is associated with increased progression-free survival and improved overall survival as part of combined modality therapy.
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Optimal timing of radiotherapy for low-grade glioma has historically remained controversial owing to concerns of potential side effects and malignant
Low-Grade Glioma Radiotherapy Treatment and Trials
Section snippets
Key points
Prognosis: Understanding who to treat
WHO grade II low-grade gliomas encompass a variety of tumors with different behaviors and prognoses. Patients with higher risk features for tumor progression are presumed to receive the greatest benefit from therapeutic intervention, but of course this specific hypothesis has not been tested. In 2002, Pignatti and colleagues3 performed a multivariate analysis from the EORTC 22844 and 22845 trials reporting 5 unfavorable prognostic factors for survival: age 40 years or older, astrocytoma
The role of radiotherapy for low-grade gliomas
The goals of RT for low-grade glioma are to improve tumor control and survival while preventing/delaying malignant transformation and limiting the acute and late effects of treatment that may degrade quality of life. Thus, understanding current data on RT for low-grade glioma is critical for informing treatment decisions. Multiple randomized, clinical trials have been published examining the roles of and dosing for RT in low-grade glioma (Table 1). The NCCTG/RTOG/ECOG trial randomized 203 adult
Technological advances of radiotherapy: intensity-modulated radiotherapy, proton therapy, and carbon therapy
Because patients with low-grade glioma may live for many years, it is important not only to improve survival outcomes, but also to minimize RT-related late effects. Advances in RT delivery systems allow for more conformal radiation treatment planning to maximize RT doses to target volumes while minimizing dose to surrounding normal structures. Intensity-modulated RT has been frequently used for the treatment of adult and pediatric brain tumors and in many studies reported to offer improved
Ongoing radiotherapy trials for low-grade glioma
Based on the results of previously discussed studies, ongoing trials are now comparing photons versus protons and evaluating the role of adjuvant TMZ (Table 2). NRG-BN005 (NCT03180502) is a phase II randomized trial of proton versus photon therapy for IDH-mutant low- and intermediate-grade gliomas using 54 Gy. The primary endpoint is to assess whether proton therapy preserves cognitive outcomes over time as measured by the Clinical Trial Battery Composite score, which is calculated from the
Summary
Recent studies have broadened our understanding of both the diagnosis and treatment of low-grade glioma. Molecular biomarkers play a vital role in the prognostication of low-grade glioma. Treatment options for low-grade glioma include surgery, observation (in highly selected subsets), radiotherapy, and/or chemotherapy. The preponderance of data suggest that, for those needing either RT or chemotherapy, the combination is the superior approach. Treatment decisions including RT must consider all
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Funding: None.
Conflict of Interest: Dr T.J.C. Wang reports personal fees and nonfinancial support from AbbVie, nonfinancial support from Merck, personal fees from AstraZeneca, personal fees from Doximity, nonfinancial support from Novocure, personal fees and nonfinancial support from Elekta, and personal fees from Wolters Kluwer, outside the submitted work. Dr M.P. Mehta reports consulting fees from Abbvie, Celgene, Tocagen; DSMB for Monteris; and stock options from Oncoceutics for being on the Board of Directors.