Intensity‐modulated radiotherapy (IMRT) in pediatric low‐grade glioma

Abstract

BACKGROUND The objective of this study was to evaluate local control and patterns of failure in pediatric patients with low‐grade glioma (LGG) who received treatment with intensity‐modulated radiation therapy (IMRT). METHODS In total, 39 children received IMRT after incomplete resection or disease progression. Three methods of target delineation were used. The first was to delineate the gross tumor volume (GTV) and add a 1‐cm margin to create the clinical target volume (CTV) (Method 1; n = 19). The second was to add a 0.5‐cm margin around the GTV to create the CTV (Method 2; n = 6). The prescribed dose to the GTV was the same as dose to the CTV for both Methods 1 and 2 (median, 50.4 grays [Gy]). The final method was dose painting, in which a GTV was delineated with a second target volume (2TV) created by adding 1 cm to the GTV (Method 3; n = 14). Different doses were prescribed to the GTV (median, 50.4 Gy) and the 2TV (median, 41.4 Gy). RESULTS The 8‐year progression‐free and overall survival rates were 78.2% and 93.7%, respectively. Seven failures occurred, all of which were local in the high‐dose (≥95%) region of the IMRT field. On multivariate analysis, age ≤5 years at time of IMRT had a detrimental impact on progression‐free survival. CONCLUSIONS IMRT provided local control rates comparable to those provided by 2‐dimensional and 3‐dimensional radiotherapy. Margins ≥1 cm added to the GTV may not be necessary, because excellent local control was achieved by adding a 0.5‐cm margin (Method 2) and by dose painting (Method 3). Cancer 2013;119:2654–2659. © 2013 American Cancer Society.

SIOP PODC Adapted treatment guidelines for low grade gliomas in low and middle income settings

“…Most trials however, have used doses ranging from 45‐ 54 Gy in 1.8 Gy per fraction. In HIT LGG 96 trial, no difference was observed between a total dose of 50.4 Gy and 54 Gy and this has been confirmed in other studies . 50.4 Gy in 1.8Gy per fraction is therefore the recommendation on current studies, with doses less than that(45Gy) reserved for younger children (< 5 years of age).…”

“…This margin accounts for set up error and depends on the quality of the immobilisation device, the accuracy of radiotherapy equipment (e.g. gantry, couch and lasers) and the ability of centres to perform portal imaging for geometric verification during treatment . For centres without regular portal imaging for verification, the PTV margin should not be less than 5mm, and where there is any doubt as to any of the accuracy measures above, then the PTV margin should not be less than 10mm.…”

Early treatment of complex located pediatric low‐grade gliomas using iodine‐125 brachytherapy alone or in combination with microsurgery

“…concepts currently in use [1,6,[9][10][11][12], ongoing interest exists to further expand the platform of localized treatment concepts for PLGG patients. A previously published pilot study has suggested that low-dose rate stereotactic Iodine-125 brachytherapy (SBT) allowing precise application of ablative tumor doses with maximum sparing of surrounding normal tissues might contribute to the spectrum of localized treatment concepts for complex located PLGGs; in that study SBT was used either alone in case of small-sized unresectable tumors or coupled with best safe resection (in case of larger tumor volumes) and has turned out to be feasible and safe [13].…”

“…In case of incompletely resectable or unresectable tumors, however, PFS becomes significantly shorter leading to the initiation of adjuvant treatment concepts including chemotherapy or radiotherapy relatively early during the history of the disease . Given the non‐negligible risk of short‐ and long‐term side effects of adjuvant treatment concepts currently in use , ongoing interest exists to further expand the platform of localized treatment concepts for PLGG patients. A previously published pilot study has suggested that low‐dose rate stereotactic Iodine‐125 brachytherapy (SBT) allowing precise application of ablative tumor doses with maximum sparing of surrounding normal tissues might contribute to the spectrum of localized treatment concepts for complex located PLGGs; in that study SBT was used either alone in case of small‐sized unresectable tumors or coupled with best safe resection (in case of larger tumor volumes) and has turned out to be feasible and safe .…”

Conformal Radiation Therapy for Pediatric Patients with Low-Grade Glioma: Results from the Children's Oncology Group Phase 2 Study ACNS0221

“…8,9 Chemotherapy is therefore the standard postsurgical modality for young patients with PLGG and is aimed at improving PFS and delaying the use of RT. 10 Improved imaging, along with modern treatment planning and delivery techniques such as 3-dimensional conformal RT (3D-CRT), 11 stereotactic RT, 12,13 intensity modulated RT (IMRT), 14 and proton therapy 15,16 allow the delivery of more conformal treatments for patients with PLGG. The use of tighter treatment volumes is expected to be associated with fewer long-term adverse effects.…”