What are the indications for axillary dissection in breast cancer?

Indications for Axillary Dissection in Breast Cancer

Axillary lymph node dissection (ALND) is now indicated only in specific high-risk scenarios: patients with biopsy-proven axillary disease, those with ≥3 positive sentinel lymph nodes, and selected patients with residual disease after neoadjuvant chemotherapy. 1

Modern Paradigm Shift: When ALND is NOT Required

The role of axillary dissection has dramatically narrowed over the past two decades. The following patients can safely avoid ALND:

Patients with 1-2 Positive Sentinel Nodes

For patients with T1-T2 tumors, ≤2 positive sentinel lymph nodes, undergoing breast-conserving surgery with whole-breast radiation and systemic therapy, sentinel lymph node biopsy (SLNB) alone without completion ALND is recommended. 2, 1 This is based on the landmark Z0011 trial, which demonstrated no survival differences at 10-year follow-up, with only 1.5% ipsilateral axillary recurrence in the SLNB-alone group versus 0.5% in the ALND group (P=0.28). 1

Patients with Micrometastases

• For treatment-naïve patients with micrometastases (0.2-2.0 mm) in sentinel nodes, no completion ALND is required, as micrometastases are prognostically equivalent to N0 disease. 2
• Critical caveat: Micrometastases after neoadjuvant therapy indicate non-pathological complete response and require different management than treatment-naïve micrometastases. 2

Selected Low-Risk Patients: Complete Omission of Axillary Surgery

Patients meeting ALL of the following criteria can safely omit SLNB entirely: age ≥50 years, tumor size ≤2 cm, grade 1-2 disease, hormone receptor-positive, HER2-negative, invasive ductal carcinoma, negative preoperative axillary ultrasound, and breast-conserving surgery planned. 1 The SOUND and INSEMA trials demonstrated 5-year invasive disease-free survival of 91.9% without axillary surgery versus 91.7% with SLNB (HR 0.91,95% CI 0.73-1.14). 1

Absolute Indications for ALND

Biopsy-Proven Axillary Disease

• Patients with clinically or radiologically abnormal lymph nodes confirmed by fine-needle aspiration or core needle biopsy require ALND. 1
• Routine axillary ultrasound should always be performed before starting any treatment to obtain maximum information about axillary status. 1

Three or More Positive Sentinel Nodes

• Patients with ≥3 positive sentinel lymph nodes require completion ALND. 1
• This threshold is based on the Z0011 trial exclusion criteria, which only validated omission of ALND for 1-2 positive nodes. 1

Residual Disease After Neoadjuvant Chemotherapy

• For initially node-positive patients treated with neoadjuvant chemotherapy who do not achieve complete pathologic response in the axilla, ALND may be indicated. 3
• Technical requirements for post-neoadjuvant SLNB: Use dual-tracer technique (blue dye and radioisotope), remove at least 3 sentinel lymph nodes, and ensure directed removal of the previously biopsied/marked lymph node with a clip. 1
• Clip placement in the biopsied lymph node before neoadjuvant therapy is strongly recommended to improve accuracy. 1

Mastectomy Patients with Positive Nodes

• For patients undergoing mastectomy (not breast-conserving surgery) with positive sentinel nodes, ALND remains standard unless the patient meets specific trial criteria. 1

Special Populations

Ductal Carcinoma In Situ (DCIS)

• Patients with apparent pure DCIS should not undergo axillary dissection in the absence of evidence of invasive cancer or proven axillary metastatic disease. 1
• SLNB should be considered in DCIS patients treated with mastectomy or excision in an anatomical location that would compromise a future sentinel lymph node procedure. 1

Elderly or High-Risk Comorbidity Patients

• Axillary procedures may be considered optional in patients with particularly favorable tumors, elderly patients, or patients with serious comorbid conditions, though these patients have increased risk for ipsilateral lymph node recurrence. 2

Technical Standards When ALND is Performed

Anatomic Extent

• Level I and II dissection should include tissue inferior to the axillary vein, extending from the latissimus dorsi muscle laterally to the medial border of the pectoralis minor muscle. 4
• Extension to Level III nodes is indicated only if gross disease is apparent in Level II nodes. 4

Lymph Node Yield

• At least 10 lymph nodes must be examined for accurate axillary staging during modified radical mastectomy or formal ALND. 4
• This 10-node threshold represents optimal quality for axillary examination and is typically achieved through level I/II dissection. 4

Critical Morbidity Considerations

SLNB significantly reduces complications compared to ALND: 38% risk reduction for lymphedema, decreased shoulder stiffness and pain, and reduced sensory neuropathy. 2 When axillary surgery is omitted entirely, morbidity is further reduced: arm/shoulder mobility restriction (2.0% vs 3.5% with SLNB), lymphedema (1.8% vs 5.7%), and arm/shoulder pain (2.0% vs 4.2%). 1

Common Pitfalls to Avoid

• Incomplete anatomic dissection: Failure to dissect to appropriate anatomic boundaries may result in inadequate nodal sampling. 4
• Omitting preoperative axillary ultrasound: This critical step identifies patients who need biopsy confirmation before proceeding with SLNB alone. 1
• Failing to clip biopsied nodes before neoadjuvant therapy: This compromises the accuracy of post-treatment SLNB. 1
• Applying Z0011 criteria to mastectomy patients: The trial only validated SLNB alone for breast-conserving surgery with whole-breast radiation. 1
• Not discussing adjuvant therapy before omitting SLNB: When axillary surgery is omitted, nodal status remains unknown and cannot guide systemic therapy escalation. 1