Surgical Management of the Axilla in HR+/HER2– Breast Cancer in the Z1071 Era: A Propensity Score-Matched Analysis of the National Cancer Database

Background Axillary management varies between sentinel lymph node biopsy (SLNB) and axillary lymph node dissection (ALND) for patients with clinical N1 (cN1), hormone receptor-positive (HR+), human epidermal growth factor receptor 2 (HER2)/neu-negative (HER2–), infiltrative ductal carcinoma (IDC) who achieve a complete clinical response (cCR) to neoadjuvant systemic therapy (NAST). This study sought to evaluate clinical practice patterns and survival outcomes of SLNB versus ALND in this patient subset. Methods Patients with cN1, HR+/HER2–, unilateral IDC demonstrating a cCR to NAST were identified from the 2012–2017 National Cancer Database (NCDB) and stratified based on final axillary surgery management (SLNB vs ALND). After propensity score-matching, overall survival (OS) was compared using a Kaplan-Meier analysis, and significant OS predictors were identified using Cox regression. Results Of the 1676 patients selected for this study, 593 (35.4%) underwent SLNB and 1083 (64.6%) underwent ALND. Use of SLNB increased by 28 % between 2012 and 2017. Among a total of 584 matched patients, 461 matched ypN0 patients, and 108 matched ypN+ patients, mean OS did not differ between SLNB and ALND (all patients [92.1 ± 0.8 vs 90.2 ± 1.0 months; p = 0.157], ypN0 patients [92.4 ± 0.8 vs 89.9 ± 0.9 months; p = 0.105], ypN+ patients [83.5 ± 2.3 vs 91.7 ± 2.7 months; p ± 0.963). Cox regression identified age, Charlson score, clinical T stage, and pathologic nodal status as significant predictors of OS. Conclusion The final surgical management strategy used for cN1, HR+/HER2– IDC patients who achieved a cCR to NAST did not have a significant impact on survival outcomes in this analysis. Potential opportunities for de-escalation of axillary management among this patient subset exist, and validation studies are needed.