Integrated Preoperative Diagnostic and Pathological Evaluation for Sentinel Node Navigation Surgery in Early Gastric Cancer: Early Experience from the FLECSS Trial.

BACKGROUND: Accurate preoperative diagnostic and pathological evaluation are essential for sentinel node navigation surgery (SNNS) in patients with early gastric cancer (EGC). This study developed and validated a standardized integrated preoperative diagnostic and pathological evaluation protocol to assess its feasibility and diagnostic concordance. METHODS: This retrospective analysis included 60 consecutive patients with cT1N0M0 EGC from the prospectively collected Fluorescence-guided Laparoscopic-Endoscopic Cooperative Sentinel Lymph Node Navigation Surgery Strategy (FLECSS) trial database between February 2024 and December 2025. All patients underwent standardized multimodal preoperative assessment using white-light endoscopy, magnifying endoscopy with image-enhanced endoscopy, endoscopic ultrasonography, and contrast-enhanced computed tomography. Intraoperative sentinel basin nodes (SBNs) and basin nodes (BNs) underwent frozen-section examination, followed by serial postoperative pathological evaluation with hematoxylin-eosin and immunohistochemical staining. Residual adipose tissue within the SLB was systematically examined to identify occult basin nodes (OBNs). Diagnostic concordance between preoperative assessment, intraoperative pathology, and final postoperative pathology was evaluated. RESULTS: All patients successfully underwent SLB identification. Preoperative assessment demonstrated excellent agreement with postoperative pathology for tumor size (ICC=0.904), excellent agreement for histological differentiation (Kappa=0.833; accuracy, 91.7%), and substantial agreement for invasion depth (Kappa=0.667; accuracy, 83.3%). Intraoperative evaluation identified a mean of 8.2 lymph nodes per patient, whereas postoperative serial examination increased the mean nodal yield to 14.5 by detecting an additional 6.3 OBNs per patient. Four patients (6.7%) had SBN metastases detected intraoperatively and underwent immediate conversion to radical gastrectomy with D2 lymphadenectomy; one patient harbored an additional non-sentinel lymph node micrometastasis. Complete concordance was observed between intraoperative frozen-section and definitive postoperative pathological findings. CONCLUSION: An integrated workflow combining multimodal preoperative assessment with standardized pathological evaluation of the SLB is feasible and demonstrated high diagnostic concordance in patients undergoing LECS-SNNS for EGC. Larger prospective multicenter studies with long-term follow-up are warranted to validate its oncological safety.