Is sentinel lymph node biopsy (SLNB) still recommended for patients after post neoadjuvant chemotherapy?

Sentinel Lymph Node Biopsy After Neoadjuvant Chemotherapy

Sentinel lymph node biopsy (SLNB) is recommended after neoadjuvant chemotherapy (NAC) in patients with clinically node-negative disease, but should be used with caution in those with initially node-positive disease who convert to clinically node-negative status after NAC. 1

Recommendations Based on Initial Nodal Status

Initially Clinically Node-Negative Patients

• SLNB after NAC is appropriate and has similar false-negative rates (5.9%-12%) compared to upfront surgery 1
• This approach reduces unnecessary axillary lymph node dissections (ALND) and associated morbidity 1, 2
• Recent data shows performing SLNB after NAC rather than before NAC results in fewer ALNDs (7.4% vs 29.9%) and is associated with better overall survival 2

Initially Clinically Node-Positive Patients Who Convert to Clinically Negative

• SLNB may be performed after NAC if specific conditions are met:
  • The previously biopsied/clipped node is removed 1
  • A dual tracer method (blue dye plus radioisotope) is used 1
  • At least 3 sentinel nodes are removed 1
• Without these conditions, the false-negative rate ranges from 7.3% to 14.2%, which many experts consider unacceptably high 1
• The ACOSOG Z1071 trial showed a detection rate of 93% with an initial false-negative rate of 13%, which improved to 9% when 3+ SLNs were removed 1

Initially Clinically Node-Positive Patients with Extensive Disease

• For patients with initially extensive nodal involvement (cN2-3) or inflammatory breast cancer:
  • Standard axillary lymph node dissection remains the recommended approach after NAC, regardless of clinical response 1
  • SLNB is not recommended for inflammatory breast cancer patients after NAC 1

Technical Considerations for SLNB After NAC

• Dual tracer mapping technique (combining blue dye and radioisotope) significantly improves accuracy 1
• Removal of at least 3 sentinel nodes reduces false-negative rates 1
• Intraoperative frozen section examination of sentinel nodes has shown 91.2% accuracy 3
• Targeted removal of previously marked positive nodes along with SLNs further improves accuracy 1

Management Based on SLNB Results After NAC

• If SLNB is negative after NAC, axillary dissection can be safely omitted 1, 4
• If SLNB is positive (including micrometastatic disease) after NAC, complete axillary lymph node dissection is currently recommended 1
• If SLNB mapping fails after NAC, standard axillary dissection should be performed 1

Cautions and Limitations

• The false-negative rate of SLNB after NAC ranges from 7.14% to 12.6% across studies 3, 5, 6
• Hormone receptor status, particularly progesterone receptor positivity, has been associated with higher false-negative results 3
• Patients should be informed that this approach, particularly in initially node-positive disease, is still evolving 1
• Axillary ultrasound alone cannot replace SLNB after NAC due to variable sensitivity and specificity 1

Conclusion

SLNB after NAC is a reliable approach for axillary staging in initially clinically node-negative patients. For initially node-positive patients who convert to clinically node-negative status, SLNB can be considered with specific technical modifications to improve accuracy. However, complete axillary dissection remains the standard for patients with extensive initial nodal involvement or those with positive SLNB after NAC.