De-escalating the axilla: oncologic and morbidity outcomes of targeted axillary dissection versus axillary lymph node dissection following neoadjuvant systemic therapy in clinically node-positive breast cancer within a single institution.

BACKGROUND: Axillary lymph node dissection (ALND) has been standard for regional control in clinically node-positive breast cancer, but causes significant morbidity, including lymphedema and arm dysfunction. Targeted axillary dissection (TAD) is a less invasive alternative after neoadjuvant systemic therapy (NST), which can downstage nodal disease. Emerging evidence suggests that TAD offers oncologic outcomes similar to ALND with less morbidity. METHODS: We conducted a retrospective cohort study of patients with clinically node-positive (cN1) breast cancer treated between 2017 and 2025 at the Montefiore Einstein Breast Care Center who received NST followed by surgery. Patients were categorized based on axillary surgical procedure (TAD or ALND) and evaluated for oncologic and morbidity outcomes. Axillary procedure selection was based on both clinical staging and response to neoadjuvant therapy. Morbidity endpoints include lymphedema, upper extremity functional impairment or range of motion limitations, compression sleeve use, rehabilitation referral, and changes in L-Dex scores. Lymphedema was diagnosed by comparing preoperative and postoperative L-Dex scores, with a change of six or more indicating diagnosis. Patient data were collected for a mean follow-up of four years. RESULTS: Of 256 patients, 136 (53.1%) underwent TAD, 14 SLNB (5.5%), and 106 ALND (41.4%). ALND had higher clinical tumor stages (p = 0.042) and a larger number of nodes removed (4.5 vs 15.3, p < 0.001). Pathologic complete response (pCR) and axillary complete response rates were higher with TAD (pCR:46% vs. 10.4%, p < 0.001; axillary CR: 64% vs. 12.3%). ALND was associated with higher rates of lymphedema (27.4% vs. 12.7%, p = 0.002), upper-extremity impairment (33.9% vs. 18%, p < 0.001), and rehabilitation referral (39.6% vs. 21.3%, p = 0.005). ALND led to a higher mean postoperative L-Dex score change (5.5 vs. 3.2; p = 0.042), reflecting greater lymphatic dysfunction. CONCLUSION: In cN1 patients treated with NST, TAD was associated with significantly lower rates of lymphedema and upper extremity morbidity compared to ALND, while also demonstrating higher pathologic and axillary complete response rates. These key findings emphasize the benefit of selective axillary de-escalation with TAD, supporting its role in reducing treatment-related morbidity while maintaining oncologic safety.