Axillary Management After Neoadjuvant Endocrine Therapy in HR-Positive/HER2-Negative Breast Cancer

Area of Science:

• Oncology
• Breast Cancer Research
• Surgical Oncology

Background:

• Neoadjuvant endocrine therapy (NET) is a standard treatment for hormone receptor-positive/HER2-negative breast cancer.
• Axillary management following NET requires careful consideration due to differing responses compared to neoadjuvant chemotherapy.
• Limited evidence exists on optimal axillary de-escalation strategies post-NET.

Purpose of the Study:

• To review current clinical practices for axillary management after NET in hormone receptor-positive/HER2-negative breast cancer.
• To identify criteria for selective de-escalation of axillary treatment in this patient population.
• To provide evidence-based recommendations for clinical decision-making.

Main Methods:

• Narrative review utilizing targeted literature searches of major biomedical databases (PubMed/MEDLINE, Embase, Google Scholar, Cochrane Library, ClinicalTrials.gov) through April 2026.
• Prioritization of direct evidence from post-NET axillary management studies.
• Inclusion of contextual evidence from surgery-first, post-chemotherapy, and radiotherapy studies to inform decision-making.

Main Results:

• The axilla's behavior post-NET differs from post-neoadjuvant chemotherapy.
• Nodal complete response after NET is infrequent, particularly in node-positive disease.
• Limited residual nodal burden post-NET may have different implications than residual disease post-chemotherapy.

Conclusions:

• Sentinel lymph node biopsy is generally appropriate for clinically node-negative (cN0) patients post-NET.
• Selective axillary de-escalation can be considered for select cN1 patients with low nodal burden.
• Bulky nodal disease or scenarios impacting adjuvant treatment necessitate more comprehensive axillary treatment.