Axillary de-escalation after neoadjuvant chemotherapy for advanced lymph node involvement in breast cancer.

Introduction: Sentinel lymph node biopsy reduces morbidity in patients with clinically node-positive breast cancer who achieve axillary pathologic complete response following neoadjuvant therapy (NACT). De-escalation trials primarily addressed cN1 disease, with underrepresentation of cN2 disease. This study evaluates the role of de-escalation in patients with cN2 breast cancer.

Methods: A retrospective analysis of the National Cancer Database (2013-2020) included women over 18 with T1-2 invasive breast cancer and clinical N2 disease who received NACT followed by ALND or SLNB then ALND. The primary outcome was pathologic nodal status post-NACT.

Results: Of 5852 cN2 patients treated, 18.15 ​% achieved ypN0, 0.97 ​% had isolated tumor cells, 19.14 ​% were ypN1, 49.64 ​% were ypN2, and 12.20 ​% were ypN3 following NACT. Achieving ypN0 was associated with pCR in the breast, HER2-positive and triple-negative receptor status, cT2 tumors, and younger age.

Conclusion: Despite some patients with cN2 disease achieving ypN0, most exhibited residual axillary disease post-NACT. These findings indicate that axillary de-escalation may not be feasible for most patients with cN2 disease, underscoring the importance of meticulous patient selection and assessment.