Peri-Lymph Node Tattooing with Carbon Nanoparticles Suspension: A Novel Strategy for Targeted Axillary Dissection in Breast Cancer.

Background: Breast cancer is the most common malignancy in women, with neoadjuvant systemic therapy (NST) increasingly used for management. Targeted axillary dissection (TAD) is a promising approach post-NST, but current marker technologies have limitations. This study evaluated the feasibility and diagnostic efficacy of peri-lymph node tattooing with carbon nanoparticles suspension (CNS) for TAD in breast cancer patients following NST. Methods: Thirty breast cancer patients with suspicious axillary lymph nodes were prospectively included. Each underwent fine needle aspiration biopsy (FNAB) of a suspected lymph node, followed by CNS tattooing under ultrasound guidance. Patients were categorized into cN(-) and cN(+) groups based on FNAB results. Post-NST, they underwent sentinel lymph node biopsy (SLNB) with TAD or axillary lymph node dissection (ALND), with histopathological examination of removed lymph nodes. Interactive 3D surface plots were generated and the proportion of CNS-stained area was quantified to assess its distribution. Results: CNS successfully marked lymph nodes without adverse events, primarily in surrounding soft tissues. In the cN(-) group, all SLNB and TAD cases were negative for TLN. In the cN(+) group, 10/18 patients had negative TLN post-NST, while 9 had positive TLN. The method showed 88.9% sensitivity, 100% specificity, 95.5% NPV, and 100% PPV, with 96.7% overall diagnostic accuracy. Quantification of the proportion of CNS-stained area revealed 0.10 ± 0.09% in the TLN and 42.61 ± 13.45% in the surrounding tissue (p < 0.05), consistent with the interactive 3D surface plot analysis. Conclusion: Peri-lymph node tattooing with CNS is a feasible and effective strategy for TAD post-NST, improving surgical precision and reducing morbidity. Further large-scale, multi-center trials are needed to validate these findings and assess long-term outcomes.