V9: Limitations in De-escalation of Axillary Surgery in Patients with cn3 Breast Cancer Following Neoadjuvant Chemotherapy

Neoadjuvant chemotherapy (NAC) has become an important procedure in the surgical management of the axilla. Recent clinical trials have demonstrated the role of NAC in reducing morbidity by de-escalating axillary surgery in patients with cN1-cN2 disease. However, the effect of NAC on down-staging cN3 to ypN0 has not been previously described. Our study aims to describe common factors in such patients with ypN0 status.


Methods: A retrospective analysis of the National Cancer Database was performed. The study cohort consisted of women with clinical N3 breast cancer diagnosed from 2012-2018. All patients underwent neoadjuvant chemotherapy followed by axillary lymph node dissection. The primary outcome was the number of patients who achieved pN0, which was defined as the absence of residual disease on final pathology. Descriptive statistics were performed to examine possible patient and tumor characteristics associated with the primary outcome.


Results: Of the 12,794 women with cN3 breast cancer who underwent ALND after NAC, 10,262 (Group 1; 80.2%) did not down-stage to ypN0 vs 2,532 (Group 2; 19.8%) who did. Common characteristics of the latter were age 40-54 years (40.3%; mean age of 51), high socioeconomic status (30.5%), being privately insured (60.6%), and Caucasian (72%). The majority of tumors in Group 2 were high-grade/poorly differentiated (72%), triple negative (31%), and HR-/HER2+ (23.7%).


Conclusions: The rate of residual disease following NAC for cN3 disease remains high. Therefore, de-escalation of axillary surgery plays a limited role in these patients. Patient and tumor characteristics related to down-staging cN3 nodal disease have been described. Further research is warranted to determine how these findings may affect treatment and prognosis.