S570
Clinical – Head & neck
ESTRO 2026
Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, China Purpose/Objective: We hypothesized that diffusion-weighted magnetic resonance imaging (DWI)-guided dose-painting volumetric modulated arc therapy (DP-VMAT) is associated with improved local tumor control and survival in patients with unresectable locally advanced head and neck squamous cell carcinoma (HNSCC) undergoing concurrent chemoradiotherapy (CCRT). The purpose of this phase 2 randomized controlled trial was to compare the efficacy and toxicity of DWI guided DP-VMAT to conventional magnetic resonance imaging (MRI)-based VMAT in patients with unresectable locally advanced HNSCC receiving CCRT. Material/Methods: A total of 248 patients with unresectable (medically inoperable or surgery-declined), locally advanced (T3- 4b, N0-3, M0, AJCC 8th), squamous cell carcinoma of the head and neck (oral cavity, oropharynx, hypopharynx and larynx) were randomly assigned 1:1 to receive either DWI-guided DP-VMAT (intervention group or DWI-guided DP group, n = 124) or conventional MRI-based VMAT (control group, n = 124). Patients in both groups were scheduled to undergo cisplatin-based CCRT. In DWI-guided DP group, subvolume GTV-DWI (gross tumor volume in DWI) was defined as the areas within the primary gross tumor volume (GTV-p) with an apparent diffusion coefficient (ADC) below the mean ADC (ADC < mean) according to MRI before chemoradiotherapy. The dose to GTV-DWI was escalated to 77 Gy/35 fx in 2.2 Gy per fraction. In control group, the primary tumor was irradiated at 70 Gy/35 fx in 2.0 Gy per fraction. The primary endpoint was disease free survival (DFS). This trial is registered with chictr.org.cn (ChiCTR2300077064). Results: In comparison to the control group, the DWI-guided DP group demonstrated a significantly higher objective response rate (ORR, 98.4% (122/124) vs. 89.5% (111/124); P =0.006) and complete response rate (CR, 90.3% (112/124) vs. 78.2% (97/124); P = 0.009). Compared with conventional MRI-based VMAT, DWI-guided DP-VMAT significantly improved 1-year DFS (89.3% vs. 75.8%; P = 0.010), local recurrence-free survival (LRFS, 99.2% vs. 91.1%; P = 0.005), distant metastasis-free survival (DMFS, 95.4% vs. 85.5%; P = 0.012), and overall survival (OS, 99.2% vs. 93.5%; P = 0.036). No statistically significant differences in severe ( ≥ grade 3) acute and late toxic effects were observed between the two groups, and no grade 5 toxic effects occurred in both groups. Multivariate analysis identified DWI-guided DP as an independent predictor of DFS (P=0.031), LRFS (P=0.028), and DMFS (P=0.038),
Conclusion: Both the Hopkins and Christie PET-CT response scores show strong prognostic correlation with survival after radical radiotherapy for HNSCC. Despite its simplicity, the Christie score demonstrated comparable discrimination, supporting its use as a pragmatic, reproducible alternative for post-treatment response assessment. Keywords: HNSCC, Hopkins score, PET CT, IMRT/VMAT DW-MRI-Guided Dose Painting Radiotherapy in Patients With Localregional Advanced HNSCC Undergoing CCRT: A Randomized, Controlled Clinical Trial Weichang Zhu 1,2 , Feng Liu 1,2 , Hui Wang 1,2 , Huai Liu 1,2 , Yuyi Li 1,2 , Cuihong Jiang 1 , Lili He 1 , Kailin Chen 1,2 , Yanfang Qiu 1,2 , Shulu Hu 1,2 , Shuai Xiao 1 , Qi Zhao 1 , Xu Ye 1 , Changgen Fan 1 , Yanxian Li 1,2 , Wenqiong Wu 1 , Xiangwei Wu 1 , Wen Liu 1 , Xiaoyu Chen 1 , Yuchen Shi 1 , Xiaoyue Zhang 1,2 , Chao Tan 1,2 Proffered Paper 1568 1 Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, China. 2 Key Laboratory of Translational Radiation Oncology,Hunan Cancer
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