Overview

Definition:
-Targeted axillary dissection after neoadjuvant therapy (NAT) refers to a tailored surgical approach to the axilla in patients with breast cancer who have received systemic therapy before surgery
-The goal is to accurately stage the axilla and remove involved lymph nodes while minimizing morbidity, especially in cases where NAT leads to a complete nodal response.
Epidemiology:
-Neoadjuvant chemotherapy is increasingly used for locally advanced or node-positive breast cancers
-Approximately 40-60% of patients achieve a clinical complete response in the axilla after NAT, with pathological complete response (pCR) in the axilla occurring in 10-20% of cases
-This highlights the need for refined axillary staging.
Clinical Significance:
-Accurate axillary staging is crucial for guiding adjuvant therapy and predicting prognosis
-In the era of NAT, traditional axillary lymph node dissection (ALND) may lead to overtreatment in a significant proportion of patients with a nodal pCR
-Targeted axillary dissection aims to identify these patients and avoid unnecessary morbidity associated with full ALND.

Indications And Patient Selection

Pre Nat Node Positive:
-Patients with clinically or radiologically positive axillary lymph nodes prior to NAT are candidates
-This includes palpable nodes or suspicious findings on imaging (mammography, ultrasound, MRI) and cytology/histology confirmation.
Post Nat Evaluation:
-Following NAT, patients undergo reassessment of the axilla
-Those with initially positive nodes but now clinically negative nodes or residual suspicious but non-enlarged nodes are considered for targeted dissection.
Imaging And Clinical Assessment:
-Residual palpable axillary nodes or suspicious findings on post-NAT imaging (especially ultrasound-guided biopsy of formerly involved nodes) are key indicators
-Absence of palpable nodes and negative post-NAT imaging requires careful consideration.

Diagnostic Approach Post Nat

Imaging Reassessment:
-Post-NAT ultrasound and potentially MRI are essential to assess axillary status
-Serial imaging may be required to confirm resolution of suspicious nodes.
Biopsy Of Residual Nodes: If any suspicious nodes remain post-NAT, ultrasound-guided fine-needle aspiration (FNA) or core biopsy is performed for cytological/histological confirmation of residual disease.
Sentinel Lymph Node Biopsy Considerations: In selected cases where complete nodal response is suspected or confirmed by imaging and biopsy, SLNB may be considered, though its role post-NAT is evolving and often requires meticulous technique and careful patient selection.

Surgical Management Strategies

Complete Axillary Lymph Node Dissection:
-This is performed when there is residual pathologically confirmed nodal disease post-NAT, or in cases where targeted approaches are not feasible or have failed
-It involves removal of Level I, II, and III lymph nodes.
Targeted Axillary Dissection:
-This encompasses several approaches: - Sentinel Lymph Node Biopsy (SLNB): Increasingly used post-NAT, especially if axillary imaging and biopsy are negative
-Requires meticulous technique and expertise
-- Selective Lymph Node Dissection: Removal of only the nodes identified as suspicious by imaging or palpation, or those that were initially positive and have a high likelihood of containing residual disease
-- "One-Stop" Approach: Performing SLNB during the same setting as primary tumor surgery after NAT, with frozen section analysis to potentially guide immediate ALND if positive.
Technique Considerations:
-Minimally invasive techniques (e.g., video-assisted axillary dissection) are being explored
-Maintaining oncologic safety is paramount, and clear guidelines for when to proceed with full ALND vs
-targeted approaches are still evolving.

Pathological Assessment And Reporting

Staging Criteria:
-Pathological staging of axillary nodes post-NAT is critical
-Reporting should include the number of sentinel nodes examined, number of positive sentinel nodes, and number of positive non-sentinel nodes if ALND is performed.
Residual Disease Evaluation:
-Accurate identification and quantification of residual disease are vital
-Extranodal extension, lymphovascular invasion, and tumor burden are important prognostic factors.
Role Of Frozen Section: Frozen section analysis of sentinel nodes during surgery can help decide on proceeding with ALND, but its accuracy can be affected by NAT-induced changes in the nodes.

Complications And Outcomes

Morbidity Of Alnd:
-Standard ALND can lead to lymphedema, seroma, wound infection, pain, and sensory nerve damage
-These are significantly reduced with targeted dissection.
Outcomes Of Targeted Dissection: When performed appropriately, targeted axillary dissection can achieve accurate nodal staging with significantly lower morbidity compared to full ALND, particularly in patients with a pathological complete response in the axilla.
Recurrence Rates:
-Studies are ongoing to determine if less aggressive axillary surgery post-NAT impacts locoregional recurrence rates
-Current evidence suggests that for patients achieving pCR in the breast and axilla, omission of ALND may be safe.

Key Points

Exam Focus:
-Understand the rationale for targeted axillary dissection post-NAT
-Know the indications for SLNB vs
-ALND in this setting
-Recognize the importance of accurate axillary staging for treatment planning and prognosis
-Differentiate between clinical and pathological response.
Clinical Pearls:
-Always reassess the axilla post-NAT clinically and with imaging
-Involve experienced breast surgeons and radiologists
-Consider multidisciplinary team discussions for complex cases
-Be aware of ongoing clinical trials and evolving guidelines.
Common Mistakes: Performing full ALND on all patients with initially positive nodes post-NAT, overlooking residual suspicious nodes on imaging, inappropriate application of SLNB in cases with documented residual disease, and inadequate pathological assessment.