Omission of Axillary Surgery After Neoadjuvant Therapy in Her2-Positive Breast Cancer: Who Are the Candidates?

Background: This study aimed to evaluate the lymph node (LN) response in Her2-positive breast cancer patients who received neoadjuvant therapy (NAT) and to discuss if axillary staging can be omitted in these patients. Methods: This is a retrospective cohort study including patients with Her2+ breast cancer at our center from March 2022 to September 2023. Results: The study included 139 patients in the final analysis; 69.1% of the patients had HR+/Her2+ disease while 30.9% had HR-/Her2+ disease. Most of the included patients (129 patients = 92.8%) had initially node-positive or suspicious disease. A total of 112 patients (80.6%) showed clinically negative axillary LNs (cN0) after NAT. All of them showed pathologically node-negative disease. When comparing the pathological node-positive vs. -negative groups, the following was found to be statistically significant: degree of Her2 positivity, number of anti-Her2 cycles, pre- and post-neoadjuvant LN status, and primary tumor radiological and pathological response. Also, all T1 tumors before NAT showed negative LNs after NAT, but it was statistically non-significant. Conclusions: Axillary staging may be omitted in Her2+ patients with cN0 after NAT, especially those with early tumors, strong Her2+ disease, cN0 before NAT, and those in whom the primary tumor achieved a complete clinical response.