Background: Sentinel lymph node (SLN) biopsy is a diagnostic staging procedure in early-stage oral squamous cell carcinoma (OSCC). The conventional method using tracers labeled with 99mTc is limited by the’shine-through’ phenomenon, a situation where intense tracer uptake at the injection site obscures nearby lymph nodes, making them difficult to detect. This effect is particularly problematic in floor of mouth tumors, where the sentinel nodes are often located close to the primary tumor. Tracing lymphatic drainage of the tumor with superparamagnetic iron oxide nanoparticles (SPIO) in combination with magnetic resonance imaging (MRI) provides superior anatomical detail over the use of radioactive tracers, which may improve the detection of SLNs. This multicenter clinical trial aims to evaluate the diagnostic accuracy of a complete magnetic SLN biopsy procedure in early-stage OSCC.

Methods: This prospective multicenter trial will enroll 82 patients with early-stage OSCC undergoing transoral resection and SLN biopsy. The complete magnetic SLN biopsy procedure includes peritumoral SPIO injection, preoperative SPIO-enhanced magnetic resonance (MR) lymphography, and intraoperative SLN detection by a magnetometer. Results will be compared to the conventional SLN biopsy using a [99mTc]Tc-nanocolloid tracer and indocyanine green. Sensitivity, negative predictive value (NPV), interobserver reliability, and patient perspectives will be assessed.

Discussion: A complete magnetic SLN biopsy may improve staging accuracy in OSCC by addressing radiotracer limitations and potentially reducing false-negative rates. This technique could potentially be expanded to other cancers, offering a radiation-free alternative to conventional SLN biopsy methods.