Research on Omitting Sentinel Lymph Node Biopsy after Neoadjuvant Therapy in cN1 Breast Cancer Patients

Some patients with clinically node-positive (cN1) breast cancer (BC) can achieve axillary pathological complete response (apCR) in axillary lymph nodes (ALNs) after neoadjuvant therapy (NAT). This study investigated predictors of post-NAT pathological node-negative (ypN0) status in cN1 breast cancer patients to identify candidates for omitting sentinel lymph node biopsy (SLNB).

This study included patients diagnosed with stage cT1-4 N1 breast cancer who received NAT followed by breast surgery and axillary lymph node dissection (ALND) at the Breast Surgery Department of the Affiliated Hospital of Southwest Medical University between January 2020 and April 2025. Univariate and multivariate logistic regression analyses were conducted to identify factors predictive of ypN0 status across different molecular subtypes.

This study enrolled 357 patients: 147 achieved ycN0 after NAT, while 210 remained ycN1. Multivariate analysis revealed: in ycN0 patients, only breast pathological complete response(bpCR) predicted ypN0 (OR: 0.151, 95% CI: 0.055-0.419); in ycN1 patients, both bpCR (OR: 0.038, 95% CI: 0.015-0.098) and MRI radiological complete response of lymph nodes (MRI-rCR(LN))(OR: 0.36, 95% CI: 0.156-0.832) were significant predictors. Univariate analysis identified ten ypN0-associated factors including bpCR. Luminal B HER2+ subtypes showed significantly higher ypN0 rates versus other subtypes.

Specific predictors (notably bpCR and MRI-rCR(LN)) are strongly associated with ypN0 in cN1 BC post-NAT, with Luminal B HER2+ patients demonstrating superior response rates. These findings support selective SLNB omission in cN1 patients achieving these key response markers.