Nanoplatforms for Sentinel and Tumor-Draining Lymph Node Mapping: From Visualization to Pathway-Informed Staging

Accurate identification of sentinel lymph nodes (SLNs) and tumor-draining lymph nodes (TDLNs) is central to oncologic staging, treatment stratification, and surgical decision-making. However, conventional radiotracer- and dye-based approaches remain limited by suboptimal signal specificity, inflexible workflows, and reduced reliability in anatomically complex or therapy-altered lymphatic networks. Nanoparticle-based lymphatic tracers address these limitations by enabling controllable lymphatic transport, stable intranodal retention, and multimodal signal generation, thereby expanding the precision and applicability of SLN/TDLN detection. This review analyzes recent advances in carbon-based, magnetic, metal/metal-oxide, polymeric/organic, and bio-derived or biomimetic nanoparticles for lymph node mapping, with emphasis on how material composition, surface engineering, and physical contrast mechanisms translate into clinically actionable imaging performance. Shared design principles underlying three key objectives are further synthesized: sensitive detection of early and occult nodes, reliable discrimination of metastatic involvement with improved staging accuracy, and robustness across delayed surgery, neoadjuvant therapy, and multi-step clinical workflows. Collectively, these advances position lymphotropic nanoparticles as a mechanistically grounded and clinically promising platform for extending both the accuracy and operational boundaries of SLN/TDLN assessment.