What are the current strategies for axillary management in breast cancer?

Current Strategies for Axillary Management in Breast Cancer

Sentinel lymph node biopsy (SLNB) is the standard of care for axillary staging in early, clinically node-negative breast cancer, and completion axillary lymph node dissection (ALND) is no longer required for patients with low axillary disease burden (micrometastases or 1-2 positive sentinel nodes) who receive breast-conserving surgery with whole breast radiation. 1, 2

Core Principles of Modern Axillary Management

The fundamental shift in axillary management prioritizes de-escalation to reduce morbidity while maintaining oncologic safety. This approach recognizes that SLNB provides equivalent staging accuracy to ALND while significantly reducing complications including lymphedema (38% risk reduction), shoulder stiffness, pain, and sensory neuropathy. 2, 3

Algorithm for Clinically Node-Negative Disease

Step 1: Initial Assessment

• Confirm clinical node-negative status through physical examination 2
• If nodes are suspicious on imaging, obtain pathologic confirmation via ultrasound-guided fine needle aspiration (FNA) or core biopsy before proceeding 4, 5

Step 2: Sentinel Lymph Node Biopsy

• Perform SLNB as the standard staging procedure for all clinically node-negative patients 1, 2
• Use H&E staining alone for treatment decisions; do not routinely perform cytokeratin immunohistochemistry as it does not improve 5-year overall survival 2

Step 3: Management Based on SLNB Results

If SLN is negative:

• No further axillary surgery required 2
• Proceed with appropriate breast surgery and systemic therapy based on tumor characteristics 2

If SLN shows micrometastases (0.2-2.0 mm) in treatment-naïve patients:

• No completion ALND required, as micrometastases are prognostically equivalent to N0 disease 2
• Critical caveat: This applies only to treatment-naïve patients; micrometastases after neoadjuvant therapy indicate non-pathological complete response and require different management 2

If SLN shows 1-2 positive nodes in patients meeting specific criteria:

• No completion ALND required if ALL of the following are met: 1, 2
  • T1 or T2 tumors
  • ≤2 positive sentinel nodes
  • Undergoing breast-conserving surgery
  • Receiving whole breast irradiation
  • Receiving systemic therapy

If SLN shows >2 positive nodes or does not meet above criteria:

• Consider completion ALND or axillary radiation as valid alternatives 1

Axillary Radiation as an Alternative Strategy

Axillary radiation is a valid alternative to completion ALND in patients with positive SLNB, irrespective of the type of breast surgery performed. 1 This represents a major controversy in current practice, as the AMAROS trial demonstrated noninferiority of radiotherapy compared to ALND for locoregional control. 3

The choice between ALND and axillary radiation should consider:

• Patient preference regarding surgical versus radiation morbidity 1
• Need for complete pathologic staging information 3
• Access to experienced radiation oncology teams 3

Special Populations and Controversies

Neoadjuvant Chemotherapy Setting

The role of SLNB after neoadjuvant chemotherapy remains controversial with discordant trial results. 3 Current evidence suggests:

• SLNB can be performed after neoadjuvant therapy in initially node-positive patients who achieve clinical complete response 3
• Removal of the clipped node (marking the initially positive node) improves accuracy 6
• The TAXIS trial is investigating whether tailored axillary surgery (TAS)—removing the clipped node, sentinel nodes, and palpably suspicious nodes—followed by axillary radiation can safely replace ALND in clinically node-positive patients 6

Patients Who May Omit Axillary Procedures

Axillary procedures may be considered optional in: 2

• Patients with particularly favorable tumors (small, low-grade, hormone receptor-positive)
• Elderly patients
• Patients with serious comorbid conditions

Important caveat: These patients have increased risk for ipsilateral lymph node recurrence, and this must be discussed explicitly. 2

Occult Breast Cancer Presenting with Axillary Metastases

For patients presenting with axillary adenopathy without identified breast primary:

• Obtain breast MRI to identify occult primary (identifies primary in 70% of cases) 1
• If MRI-positive: treat according to clinical stage after biopsy confirmation 1
• If MRI-negative with T0,N1,M0 disease: options include either mastectomy plus ALND OR ALND plus whole breast irradiation with or without nodal irradiation 1

DCIS Management

SLNB should NOT be routinely performed in DCIS, except for: 1

• Large tumors
• High-grade tumors
• Cases requiring mastectomy

Critical Pitfalls to Avoid

1. Do not perform completion ALND reflexively for positive SLNB without first confirming the patient does not meet criteria for omitting ALND (particularly the Z0011 criteria). 1, 2

2. Do not use cytokeratin immunohistochemistry routinely for SLNB evaluation, as isolated tumor cells detected only by immunohistochemistry do not impact treatment decisions or survival. 2

3. Ensure access to experienced SLNB teams with identification rates ≥97% and false-negative rates ≤10%; refer patients to experienced centers if local expertise is insufficient. 2

4. Do not treat micrometastases after neoadjuvant therapy the same as treatment-naïve micrometastases—post-neoadjuvant micrometastases indicate residual disease requiring more aggressive management. 2

5. Do not delay or omit pathologic confirmation of suspicious nodes on imaging before proceeding directly to ALND; ultrasound-guided biopsy should be performed first. 4