A Multicenter Retrospective Study on Screening Patients Eligible for Exemption From Axillary Surgery Based on the Pathological Remission of the Breast After Neoadjuvant Therapy.

INTRODUCTION: With better responses to neoadjuvant therapy (NST), clinicians are increasingly inclined to spare axillary surgery. Yet it is not well defined whether tumor regression in the breast can serve as a reliable surrogate for nodal clearance across diverse nodal burdens at baseline and intrinsic tumor biology. PATIENTS AND METHODS: We retrospectively analyzed 864 patients treated with NST across 5 Chinese institutions. Subgroup analyses were performed according to initial nodal stage (cN0, cN1, cN2/3), molecular subtype, breast pathological response (ypT0, ypTis, or non-pCR), and final preoperative imaging. The endpoint was ypN status. RESULTS: Breast pCR was observed in 34.4%. Among cN0 patients with breast pCR, 95.6% achieved axillary pCR, reaching 100% in TNBC or HER2-positive tumors, irrespective of ypT0 or ypTis. In cN1 disease, breast pCR correlated with a 93.0% axillary pCR; notably, all ypT0 cases in TNBC/HER2-positive were node-negative. For cN2/3 patients with breast pCR, the false-negative rate of imaging in predicting nodal clearance remained below 5% for both ypT0 and ypTis. CONCLUSIONS: Selected patients may be candidates for axillary surgery omission-specifically, TNBC/HER2-positive cN0 patients with breast pCR (ypT0/is), and cN1 patients who achieve ypT0 (but not ypTis). For cN2/3 patients with breast pCR and negative post-treatment imaging, foregoing SLNB appears worth considering, though prospective data are needed to confirm safety.