Staging Criteria Before SLNB in Neoadjuvant Therapy Group
In patients receiving neoadjuvant therapy, pre-treatment sentinel lymph node biopsy (SLNB) is NOT recommended; instead, comprehensive axillary staging should be performed using ultrasound with biopsy confirmation of suspicious nodes, and SLNB should be deferred until after completion of neoadjuvant therapy. 1
Pre-Neoadjuvant Therapy Axillary Staging Requirements
Mandatory Initial Evaluation
Routine ultrasound of the regional nodal basins is strongly encouraged before initiating neoadjuvant therapy to obtain maximum information about axillary status for systemic and local treatment decisions 1
Any clinically or radiologically abnormal lymph nodes must be diagnosed by fine-needle aspiration or core needle biopsy before starting neoadjuvant therapy 1
Clip placement into the biopsied node is strongly recommended to improve the accuracy of post-neoadjuvant SLNB and ensure the originally positive node can be identified and removed 1, 2
Why Pre-Neoadjuvant SLNB is Contraindicated
The evidence is unequivocal on this point:
Pre-neoadjuvant SLNB is NOT recommended because assessment of nodal response in the axilla becomes unreliable after excision of a positive node 1
Performing SLNB before neoadjuvant therapy invalidates the RCB (Residual Cancer Burden) score and the ypN stage, potentially compromising comparisons of pathologic complete response results across different studies 1
Removing sentinel nodes before neoadjuvant therapy eliminates the ability to assess one of the most important determinants of survival post-neoadjuvant therapy—the nodal response 1
Clinical Staging Categories Pre-Neoadjuvant Therapy
Clinically Node-Negative (cN0) Patients
These patients should undergo axillary ultrasound to confirm node-negative status 1
If ultrasound identifies suspicious nodes (≤3 abnormal level I or II nodes), ultrasound-guided biopsy should be performed 1
SLNB is deferred until after neoadjuvant therapy completion, with false-negative rates of 5.9-12% similar to upfront surgery 1, 2, 3
Clinically Node-Positive (cN+) Patients
Biopsy-proven nodal metastases must be documented with core needle biopsy or fine-needle aspiration before neoadjuvant therapy 1
The biopsied node must be marked with a clip at the time of biopsy 1, 2
Post-neoadjuvant SLNB can be performed ONLY if ALL three technical criteria are met: dual tracer mapping, removal of ≥3 sentinel nodes, and removal of the previously biopsied/clipped node 1, 2, 4
Imaging Staging Requirements
Breast Cancer Patients
For tumors >2 cm with clinical node-positive disease, contrast-enhanced CT chest/abdomen/pelvis may be performed to evaluate for distant metastases, though it does not replace axillary ultrasound for local staging 1
FDG-PET/CT has pooled sensitivity of 71-88% and specificity of 69-79.3% for assessing nodal response after neoadjuvant therapy, but is not routinely used for initial staging 1
Axillary ultrasound remains the primary imaging modality for initial nodal assessment, with sensitivity ranging from 52-90% when combined with biopsy 1
Common Pitfalls and How to Avoid Them
Do not perform SLNB before neoadjuvant therapy even in clinically node-negative patients—this compromises the ability to assess treatment response and may lead to unnecessary axillary dissections 1
Do not rely on clinical examination alone—ultrasound identifies occult nodal disease in patients who are clinically node-negative 1
Do not skip clip placement in biopsied nodes—this is essential for targeted axillary dissection and reduces false-negative rates to 0-7% when the clipped node is removed 1, 2, 5
Do not assume all node-positive patients require immediate axillary dissection—those who achieve clinical complete response can safely undergo SLNB if technical criteria are met 1, 2, 3