De-escalation of axillary surgery after neoadjuvant therapy in breast cancer: long-term outcomes of sentinel lymph node biopsy alone versus complete axillary lymph node dissection.

BACKGROUND

The optimal management of axillary lymph nodes after neoadjuvant systemic therapy (NST) in breast cancer remains controversial. The oncological outcomes of sentinel lymph node biopsy (SLNB) alone compared with axillary lymph node dissection (ALND) after NST are not well established.

OBJECTIVE

This study comprehensively evaluated the long-term outcomes of SLNB alone versus ALND following NST in breast cancer patients achieving ycN0 status.

DESIGN

A retrospective, multicenter, real-world study.

METHODS

Patients initially presenting with clinically node-negative (cN0) or clinically node-positive (cN+) breast cancer who remained or converted to ycN0 after NST (2011-2022) were included. Patients were divided into SLNB-alone and ALND groups. Primary endpoints were disease-free survival (DFS) and overall survival (OS). Secondary endpoints included recurrence rates, local recurrence-free survival (LRFS), regional recurrence-free survival (RRFS), and distant metastasis-free survival (DMFS). Inverse probability of treatment weighting (IPTW) was applied to balance baseline characteristics.

RESULTS

A total of 1381 patients were included: 461 received SLNB alone, and 920 underwent ALND. Median follow-up was 34.2 months (range: 1.2-142.6 months). Local (2.8% vs 3.3%, p = 0.656) and regional (2.0% vs 1.3%, p = 0.353) recurrence rates were comparable between SLNB and ALND groups; distant metastases occurred in 5.6% versus 8.5% (p = 0.059). No significant differences in DFS, OS, LRFS, RRFS, or DMFS were observed between the SLNB-alone and ALND groups after IPTW adjustment. Subgroup analyses confirmed similar DFS or OS between the two surgical approaches across initial cN0 and cN+ subgroups; however, patients with initial cN2-3 disease exhibited inferior LRFS with SLNB alone.

CONCLUSION

SLNB alone achieves oncologic outcomes comparable to ALND in ycN0 breast cancer patients after NST, regardless of initial nodal status, with caution warranted in initial cN2-3 disease. This suggests that SLNB alone can safely substitute ALND without compromising oncologic outcomes in appropriately selected patients.