Comparing the Recurrence Patterns of Reduced-Margins vs. RTOG-Protocol in Adjuvant Chemoradiation of High-Grade Gliomas: A Multicenter, Open-Label, Randomized Controlled Trial.
In a multicenter phase III trial of 258 patients aged 18–75 years with newly diagnosed grade 3 or 4 glioma, reducing the adjuvant radiotherapy CTV margin from 2 cm to 1 cm did not significantly alter PFS, OS, or recurrence distribution, although survival estimates numerically favored the standard-margin group.
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In a multicenter phase III trial of 258 patients aged 18–75 years with newly diagnosed grade 3 or 4 glioma, reducing the adjuvant radiotherapy CTV margin from 2 cm to 1 cm did not significantly alter PFS, OS, or recurrence distribution, although survival estimates numerically favored the standard-margin group.
Research significance
The trial provides evidence that a 1-cm CTV margin does not significantly increase marginal or out-of-field recurrence; it may therefore reduce irradiation of normal brain while preserving disease control, but reduced toxicity was not reported and the confidence intervals and numerical survival trends do not establish equivalence or noninferiority.
Source abstract
BACKGROUND: Radiotherapy following maximal-safe resection is a cornerstone of treatment for high-grade gliomas (HGGs). However, the optimal clinical target volume (CTV) margin remains controversial. This study aimed to evaluate the safety, efficacy, and recurrence patterns associated with a reduced CTV margin in patients with HGGs, compared to standard RTOG-based planning. METHODS: In this multicenter, phase III randomized clinical trial, patients aged 18-75 years with newly diagnosed WHO-grade 3 or 4 gliomas were randomly assigned to receive adjuvant radiotherapy with either a standard 2-cm clinical target volume (CTV) margin (control group) or a reduced 1-cm margin (intervention group). The primary endpoint was progression-free survival (PFS), while the secondary endpoints included overall survival (OS) and patterns of recurrence. RESULTS: A total of 258 patients were enrolled, of whom 75.6% had grade 4 gliomas. After a median follow-up of 14.5 months, median PFS was 15 ± 1.25 months in the intervention group but it was 19 ± 2.71 months in the control group (hazard ratio [HR] = 1.32; 95% CI, 0.93-1.87; p = 0.121). Median OS was 22.0 ± 2.98 months in the intervention group, while it was not reached in the control group (HR = 1.52; 95% CI, 0.99-2.33; p = 0.057). Imaging progression occurred in 35% of patients in the intervention group and 32.2% in the control group (p = 0.637). In-field recurrence was the predominant pattern in both groups (84% vs. 83.8%; p = 0.829), with no significant increase in marginal or out-of-field failures associated with margin reduction. CONCLUSION: Reducing the clinical target volume (CTV) margin from 2 cm to 1 cm in the adjuvant radiotherapy of high-grade gliomas did not significantly affect progression-free survival (PFS), overall survival (OS), or recurrence patterns. These findings support the feasibility and safety of margin reduction, even in settings where three-dimensional conformal radiotherapy (3D-CRT) is the primary technique.