Neck dissections based on sentinel lymph node navigation versus elective neck dissections in early oral cancers: A randomized, multicenter, non-inferiority trial

6007 Background: The objective of the study is to evaluate the non-Inferiority of survival, the superiority of postoperative disability, and the complication of the neck in neck dissections based on sentinel lymph node navigation in early oral cancer patients, compared with standard selective neck dissections. Methods: This study was a randomized, multicenter, non-inferiority trial at 16 institutions in Japan. Eligibility criteria included histologically confirmed squamous cell carcinoma in the oral cavity; clinical categories T1 and T2, N0M0 by UICC TNM classification 7th edition, clinical depth of invasion (DOI) of T1 was over 4mm (defined as late T1); previously untreated; age at least 18 years; and written informed consent. We randomly assigned patients (1:1) to receive either sentinel lymph node biopsy (SNB) or standard selective neck dissections (ND) with stratification of T category (lateT1 vs T2) and subsite (tongue vs others). The primary endpoint was 3-year overall survival with a non-inferiority margin of 12%. Sentinel nodes (SNs) were detected using radioisotope method and examined with multislice frozen section analysis intraoperatively, following HE and cytokeratin stain for a final postoperative diagnosis. Patients with positive SNs had neck dissections in a one-stage or back up procedure. Results: Between November 2011 and January 2016, 271 patients were enrolled and randomized to SNB group (134 patients) and ND group (137 patients) with a median follow-up of 37 months (IQR 36-39). Pathological positive nodal status was 34% (46/132) in SNB group and 26% (34/133) in ND group (Chi-Square p = 0.10). 3-year overall survival in SNB group was 89% (95%CI 82-93%), which was non-inferior to that in ND group (86%, 95%CI 79-91%). 3-year relapse-free survival was 80% (95%CI 72-86%) in SNB group and 81% (95%CI 73-87%) in ND group. Arm abduction of postoperative 1 and 3 months in ND group was disturbed significantly compared with SNB group. Conclusions: SNB navigated ND could replace elective ND without survival disadvantage and reduce postoperative disability of the neck in patients with early oral cancer. Clinical trial information: 000006510.