S810
Clinical - Lung
ESTRO 2026
were well-balanced between the two groups (Table 1). As of October 30, 2025, the median follow-up was 7.5 months. Completion rates for hypo-RT were 98.9% (188/190) in the study group and 97.4% (186/191) in the control group. Subsequently, 78.4% (149/190) and 68.6% (131/191) of patients proceeded to immune consolidation therapy in the study and control groups, respectively. The incidence of G2+ respiratory toxicity was significantly lower in the study group (16.3%, 95% CI 11.1% ~ 21.6%) than in the control group (26.7%, 95% CI 20.4% ~ 33.0%) (p=0.014), with G3+ events occurring in 2.1% and 3.1% of patients, respectively. Preliminary 12-month PFS was 65.3% (95% CI: 56.4 - 75.4) in the study group and 64.2% (95% CI: 54.9 - 75.1) in the control group (p=0.910).
Proffered Paper 3155 A Phase III Randomized Trial of Adaptive Hypofractionated Radiotherapy for Stage III Non- Small Cell Lung Cancer Based on Dynamic Contrast-Enhanced MRI Bo Qiu 1 , Daquan Wang 1 , Fangjie Liu 1 , Rui Zhou 2 , Shiyang Zheng 3 , Hongmei Zhang 4 , Pengxin Zhang 1 , HaoTing Zhang 1 , Biao Xia 1 , Yu Situ 1 , Mengru Wang 1 , HaoQiang He 5 , Kangqiang Peng 5 , Shaohan Yin 5 , Chuanmiao Xie 5 , Hui Liu 1 1 Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, China. 2 Oncology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China. 3 Pulmonary Oncology, The First People’s Hospital of Foshan, Foshan, China. 4 Oncology, Air Force Hospital of Southern Theater Command of the People’s Liberation Army, Guangzhou, China. 5 Medical Imaging, Sun Yat-sen University Cancer Center, Guangzhou, China Purpose/Objective: Hypofractionated radiotherapy (hypo-RT) has shown promising efficacy when combined with immunotherapy in unresectable stage III non-small cell lung cancer (NSCLC). We hypothesized that adaptive hypo-RT, guided by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to personalize radiation dose to different tumor regions, could reduce toxicity without compromising efficacy. Material/Methods: In this prospective, randomized phase III trial, patients with unresectable stage III NSCLC were assigned 1:1 to receive definitive split-course hypo-RT, guided by either DCE-MRI (study group) or standard CT (control group). All patients received concurrent weekly chemotherapy (nab-paclitaxel plus cisplatin), followed by up to 12 months of PD-1/PD-L1 inhibitor consolidation. The hypo-RT regimen was delivered in two courses separated by a four-week break. In the study group, DCE-MRI was performed before each course to guide adaptive planning; tumor subregions with a volume transfer rate (Ktrans) ≥ 164.3 × 10 ⁻ ³ received 25 Gy/6 fractions per course (total dose 50Gy), while the remaining regions received 30 Gy in 6 daily fractions per course. In the control group, all gross tumor volumes uniformly received 30 Gy in 6 fractions per course (total dose 60Gy). The primary endpoints were the incidence of grade 2 or higher (G2+) respiratory toxicity (tested for superiority) and the 2-year progression-free survival (PFS) rate (tested for non-inferiority). We report preliminary outcomes here (NCT06545747). Results: Between August 1, 2024, and September 20, 2025, 381 patients were randomized to the study group (n=190) and the control group (n=191). Baseline characteristics
Conclusion: These preliminary results indicate that DCE-MRI–
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