Abstract:Objective To investigate and analyze the factors affecting the accuracy of sentinel lymph node biopsy (SLNB) after neoadjuvant chemotherapy (NAC) in breast cancer patients. Methods A total of 184 patients with breast cancer who underwent SLNB and axillary lymph node dissection after NAC from January 2020 to September 2022 were collected from Taihe Hospital. The tracer effect of SLNB by carbon nanoparticles combined with methylene blue in patients after NAC was analyzed, and the influencing factors were examined by logistic regression analysis. Results The detection rate of SLNB after NAC was 98.9% (182/184), with a false-negative rate of 17.5% (14/80), accuracy of 92.3% (168/182), sensitivity of 82.5% (66/80), pathological complete response rate of 18.5% (34/184), and sentinel lymph node (SLN) metastasis rate of 36.3% (66/182). The consistency between SLNB and axillary lymph node dissection results was high (Kappa=0.841, P＜0.01). The false-negative rate of SLNB after NAC differed significantly in terms of initial axillary lymph node clinical status, total SLN count, and tumor molecular subtype (P＜0.05). Initial axillary lymph node clinical status and tumor location were independent factors affecting the accuracy of SLNB after neoadjuvant chemotherapy (P＜0.05). Conclusion SLNB may accurately predict axillary lymph node metastasis after NAC in patients with negative axillary lymph node for a preliminary diagnosis. Patients with positive axillary lymph node for a preliminary diagnosis are unsuitable for SLNB whether the clinical status of axillary lymph nodes turns negative or not after NAC.