TPS6093 Background: Since patients with early-stage oral cavity cancer (OCC; T1-2N0M0; AJCC 8th ed) have a 20-30% rate of occult nodal metastases despite clinical and radiographic assessment, standard of care treatment includes elective neck dissection (END). Many patients have comprehensive surgical management of the regional cervical nodal basin even though the majority of those necks (70-80%) will not contain disease. Assessment of draining first echelon lymph nodes by sentinel lymph node (SLN) biopsy (Bx), a less invasive surgical procedure, may provide an alternative to END, while potentially reducing morbidity and cost. A decisive clinical trial comparing SLN Bx versus END can focus the HNC clinical and research community and resources on establishing the standard of care for management of the neck in early-stage OCC. Methods: In order to address the efficacy of SLN Bx in this population, we recently activated an international multi-institutional phase II/III prospective trial randomizing patients to two surgical arms: SLN Bx and END. PET/CT is an integral imaging biomarker in this trial. A node-negative PET/CT study with central read is required before randomization. Patients with a positive PET/CT central result will remain in a registry to compare imaging findings with final neck pathology. Given the current evidence available regarding morbidity for SLN Bx versus END, the phase II will determine if patient-reported neck and shoulder function and related QOL at 6 months after surgery using the Neck Dissection Impairment Index (NDII) shows a signal of superiority of SLN Bx compared to END. A total of 228 randomized patients with negative PET/CT for potential evaluation of shoulder-related morbidity with difference in 6-month NDII scores (minimum important difference ³7.5; one-sided a = 0.10; 90% power) will serve as the “Go/No-Go” decision to move forward into phase III. The phase III portion is a non-inferiority (NI) trial with disease-free survival (DFS) as the primary endpoint (NI margin hazard ratio 1.34 based on a 5% absolute difference in 2-year DFS; one-sided alpha 0.05; 80% power, and an interim look for efficacy at 67% of the events based on an O’Brien-Fleming boundary). The NDII at 6 months after surgery is a hierarchical co-primary endpoint for the phase III. Target accrual of phase III is 618 PET/CT negative patients, including those randomized in phase II (297 DFS events required for the final analysis). In addition to radiotherapy and imaging credentialing, quality assurance will include central pathology review of all negative SLN Bx cases and surgeon credentialing through an education course and SLN Bx and END case review by the surgical co-chairs. A surgical quality assurance working group will review all trial SLN Bx and END outcomes. As of 02/15/21, 7 patients have been screened and 6 of the planned 228 randomized patients in phase II have been enrolled. Clinical trial information: NCT04333537.
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