The ELIMINATE trial: A phase II/III randomized trial evaluating omission of radiotherapy to regional lymphatics in pN0/N1 neck for oral cavity carcinomas.

Abstract

TPS243 Background: Postoperative radiotherapy (PORT) improves locoregional control in oral cavity squamous cell carcinoma (OCSCC) with adverse pathological features. However, irradiation of elective regional lymphatics contributes substantially to dysphagia and long-term toxicity. In adequately dissected pN0–pN1 necks, the oncologic benefit of regional nodal irradiation remains uncertain. ELIMINATE evaluates whether omission of regional PORT maintains regional control while reducing treatment-related morbidity. Methods: ELIMINATE is an open-label, multicenter, randomized phase II/III non-inferiority trial enrolling 396 patients with resected pT1–4 OCSCC and pathological pN0–pN1 disease after adequate neck dissection (≥12 nodes in at least one hemi-neck). Eligible patients have high-risk features (positive/close margin ≤5 mm, lymphovascular invasion, perineural invasion, or pT3–4 disease) and Karnofsky performance status ≥70. Patients are randomized 1:1, stratified by T stage (T1–2 vs T3–4), nodal status (pN0 vs pN1), and margin status (free vs involved), to: Arm A (standard): IMRT to primary tumor bed and regional lymphatics (60–66 Gy in 30–33 fractions) ± weekly cisplatin (40 mg/m²) for margin-positive disease.Arm B (experimental): IMRT or brachytherapy to the primary tumor bed alone, omitting elective nodal irradiation. The primary endpoint is 2-year regional control. Secondary endpoints include locoregional control, disease-free survival, overall survival, acute toxicity (RTOG), late toxicity (LENT-SOMA), swallowing function (MDADI), and quality of life (EORTC QLQ-C30 and H&N35).The trial is powered (80%, one-sided α=0.05) to test non-inferiority with a 5% absolute margin, assuming 2-year regional control of 85% with standard PORT versus 80% with omission, allowing 10% attrition (n=396). Accrual is ongoing across participating tertiary centers. Treatment compliance, dosimetric data, toxicity, and oncologic outcomes will be reported at analysis. ELIMINATE is the first adequately powered randomized study evaluating omission of elective nodal irradiation in both pN0 and pN1 OCSCC following adequate dissection. If non-inferiority is demonstrated, this strategy may safely reduce radiation volumes, decrease swallowing morbidity, and redefine postoperative standards in selected patients. Clinical trial information: CTRI/2022/02/040311 .