Nanoparticle-assisted axillary staging: an alternative approach after neoadjuvant chemotherapy in patients with pretreatment node-positive breast cancers

In order to achieve an optimized method of axillary staging after neoadjuvant chemotherapy (NAC) in breast cancer patients with pretreatment positive axillary lymph nodes, we evaluated the feasibility and accuracy of nanoparticle-assisted axillary staging (NAAS) which combines carbon nanoparticles with standard sentinel lymph node biopsy (SLNB) with radioisotope and blue dye.Invasive breast cancer patients with pre-NAC positive axillary lymph nodes who converted to ycN0 and received surgeries from November 2020 to March 2021 were included. All patients underwent ipsilateral NAAS followed by axillary lymph node dissection. Detection rate (DR), false-negative rate (FNR), negative predictive value (NPV) and accuracy of axillary staging were calculated.Eighty of 136 (58.8%) breast cancer patients converted to ycN0 after NAC and received NAAS. The DR, NPV and accuracy was 95.0%, 93.3% and 97.4% for NAAS, respectively. And the FNR was 4.2% (2/48) for NAAS, which was lower than that of standard dual-tracer SLNB (SD-SLNB) (9.5%, 4/42). Pretreatment clinical T4 classification was a risk factor for detection failure in NAAS (p = 0.016). When patients with pretreatment inflammatory breast cancers were excluded from analysis, FNR dropped to 2.2% (1/45) for NAAS.NAAS revealed great performance in invasive breast cancer patients with pre-NAC positive axillary lymph nodes who converted to ycN0. The application of NAAS reached a better balance between more accurate axillary evaluation and less intervention. Trial registration Chictr.org.cn (ChiCTR2000039814). Registered Nov 11, 2020.