Abstract BACKGROUND Emerging evidence suggests that Tumor Treating Fields (TTFields) may potentiate radiotherapy (RT) efficacy through dual mechanisms: enhancing tumor cell chemosensitivity by modulating membrane permeability to chemotherapeutic agents, and demonstrating synergistic anti-glioma activity with ionizing radiation via suppression of DNA damage repair pathways. This study aims to utilize magnetic resonance-guided linear accelerator (MR-Linac) technology to quantify temporal variations in gross tumor volume (GTV) dynamics during concurrent chemoradiotherapy (CRT) with TTFields integration in high-grade glioma (HGG) patients, establish phenotypic correlations between volumetric evolution patterns and clinicopathological characteristics, and evaluate the therapeutic impact of TTFields augmentation on survival outcomes and recurrence patterns. MATERIAL AND METHODS This study analyzed 15 HGG patients receiving concurrent TTFields (TTF) and 15 without concurrent TTFields(non-TTF) controls undergoing MR-Linac therapy. Baseline and on-treatment GTV contours, delineated by a senior radiation oncologist following RTOG guidelines, were compared through: Dice similarity coefficient (DSC), Hausdorff distance (HD), relative volumetric change (ΔV). Comparative analyses evaluated treatment effects between TTF group versus non-TTF group, focusing on recurrence patterns and survival outcomes. RESULTS As of February 20, 2025, the TTF group showed significantly better median OS (not reached vs. 19.0 months; p=0.0091) and numerically improved PFS (13.11 vs 9.92 months; p=0.0892) compared to non-TTF controls. Recurrence patterns differed substantially: non-TTF group exhibited 40% in-field, 20% marginal, and 20% distant recurrences, while TTF group demonstrated reversed predominance with 40% distant, 27% marginal, and 6% in-field recurrences. During radiotherapy, both groups exhibited declining trends in GTV ΔV and DSC alongside increasing HD trends, with more pronounced changes observed in the TTF group compared to non-TTF. CONCLUSION TTF group correlated with improved survival and accelerated GTV regression. Statistical assessment of recurrence patterns demonstrated predominant in-field progression in non-TTF group, whereas the TTF group exhibited a higher incidence of distant progression.
Yan Chen (Wed,) studied this question.