S654
Clinical – Head & neck
ESTRO 2026
alternative when cord-prioritized plans compromise local control. Keywords: radiation myelopathy, target-prioritized strategy
evaluated associations between anatomical invasion patterns and the need for a target-prioritized plan. Results: During a median follow-up of 8.4 years, no RM occurred among all 985 patients. Of the 146 patients with tumor–cord distance ≤ 2 cm, 107 required a target-prioritized strategy, while 39 achieved protocol spinal cord limits without relaxation. Multivariable logistic regression showed that invasion of the occipital condyle, retropharyngeal lymph nodes, occipital base, bilateral carotid sheath region, and the hypoglossal canal was significantly associated with adopting a target-prioritized plan. In the target- prioritized group, median PRV Dmax, D0.03cc, and D1cc were 54.2 (IQR 52.1–57.8), 52.7 (50.3–56.4), and 50.9 (48.2–54.1) Gy, respectively. Fifteen patients (10.3%) exceeded PRV Dmax > 60 Gy, all with very small high-dose sub-volumes, and none developed RM. Five-year local control was 86% vs 93% (P = 0.82) and overall survival 74.6% vs 73% for the target- prioritized vs conventional-limit groups.
Proffered Paper 4291
Omission of elective nodal irradiation in HNSCC: long-term results and patient-level pooled analysis from 2 prospective trials (INRT-AIR & DARTBOARD) Sympascho Young 1 , Dominic Moon 1 , Chien-Yi Liao 1 , Jing Wang 1 , Liyuan Chen 1 , Mu-Han Lin 1 , Randall Hughes 1 , Chul Ahn 1 , Vladimir Avkshtol 2 , David J Sher 1 1 Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, USA. 2 Department of Radiation Oncology, Kelsey-Seybold Clinic, Houston, USA Purpose/Objective: Definitive chemoradiotherapy (CRT) for head and neck squamous cell carcinomas (HNSCC) carries significant long-term toxicities, with elective neck irradiation (ENI) serving as a major contributor to integral dose and the irradiation of critical organs-at-risk. Involved nodal radiotherapy (INRT) is a novel investigational approach that omits ENI, holding potential to improve short- and long-term morbidity and reduce radiotherapy-induced immunosuppression. Herein we report on long-term outcomes from two prospective trials conducted at UT Southwestern studying the INRT paradigm. Material/Methods: A patient-level pooled analysis was conducted for 2 prospective trials that used INRT: INRT-AIR1 (NCT03953976) and DARTBOARD2 (NCT04883281). Eligibility criteria for the 2 trials were identical: newly diagnosed oropharynx, larynx, or hypopharynx squamous cell carcinoma (SCC) receiving definitive RT or CRT, ECOG 0-2. All stages I-IVB were included except T1-2N0 glottic larynx. All patients underwent PET-CT and neck CT. The INRT approach is described as follows: involved and suspicious lymph nodes were treated to 70 Gy and 66.5 Gy (INRT-AIR)/56-63 Gy (DARTBOARD), respectively1,2. Suspicious lymph nodes were identified using both radiologic criteria and an in-house artificial intelligence (AI)-based classification model. All identified lymph nodes within an involved station were also treated. Standard ENI volumes were contoured for all patients on INRT-AIR (n=67) for dosimetric analysis. Results: The pooled analysis included 117 patients, with 86 oropharynx (n=77 p16+), 26 larynx and 5 hypopharynx HNSCC. Median age was 62 (IQR: 55-69), 82% were male, and 91.5% were treated with concurrent chemotherapy. Median follow-up for surviving patients were 3.4 (entire cohort, n=117), 5.0 (INRT-AIR, n=67)
Conclusion: With dose–volume control and IGRT, no myelopathy occurred despite relaxing cord PRV limits for cord- adjacent NPC. Target-prioritized planning is a feasible
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