Sentinel Lymph Node Detection in Gastric Cancer Using a Dual Tracer (Superparamagnetic Iron Oxide and Methylene Blue): A Prospective Study With Histological and OSNA Validation

Gastric cancer (GC) remains an oncological challenge, where lymph node involvement is a key prognostic factor. Sentinel lymph node (SLN) mapping may improve staging and reduce surgical morbidity. This study evaluated a dual-tracer technique - superparamagnetic iron oxide (SPIO) and methylene blue - for ex vivo SLN detection in GC, analysed the performance of one-step nucleic acid amplification (OSNA) versus conventional histology and applied pooling analysis with OSNA in non-sentinel nodes. The aim of this prospective study was, firstly, to evaluate the accuracy of ex vivo SLN detection using a novel dual tracer: SPIO not previously used for this pathology, combined with methylene blue. Secondly, to perform a diagnostic concordance analysis between the results of the conventional histological haematoxylin-eosin (H-E) study versus the OSNA (One Step Nucleic Acid Amplification) molecular method, for the detection of lymph node metastases in patients with gastric cancer undergoing surgery with curative intent and lymphadenectomy.