Evaluation of residual axillary lymph node metastases after neoadjuvant treatment in breast cancer

Abstract

Background: The present study aims to evaluate the volume of residual axillary nodal disease after neoadjuvant chemotherapy (NACT) in breast cancer. Methods: Predictive factors for low-volume residual axillary nodal disease were analyzed in patients with histologically proven breast cancer (cT1-3 cN0-2) who were treated with NACT and surgery between 2015 and 2019. Results: A total of 734 patients were analysed. Breast pathological complete response (pCR) was achieved in 35.1%, with 31.5% showing no residual tumour in the breast or axillary lymph nodes (LNs). Breast and axillary pCR rates varied according to receptor subtype, with the highest rates found in HER2+ and hormone receptor (HR) negative tumours. Among 385 patients presenting with axillary metastases at diagnosis, 41.0% achieved axillary pCR, and 38.4% had 1-3 metastatic LNs. Predictive factors for axillary pCR included cN stage, HR status, ycN status, and breast pCR. For breast pCR patients with cN+ at presentation, the rate of axillary pCR was 81.1%. After NACT, 68.7% of patients with >2 metastatic LNs at diagnosis had 0-3 residual LNs. Conclusion: We conclude that breast pCR, HER2+, HR negative breast cancer, <3 metastatic axillary LNs at diagnosis, and complete axillary imaging response after NACT were associated with axillary pCR rates and low probability of >3 positive LNs. Similarly, our study showed that axillary pCR in patients with more than two metastatic LNs was comparable to that of patients with 1-2 metastatic LNs highlighting an opportunity to tailor axillary surgery in this subgroup.