Omission of Axillary Lymph Node Dissection in Patients with pT0-2 ER+/HER2- Breast Cancer with 3-5 Positive Lymph Nodes Undergoing Adjuvant Systemic Therapy and Radiation Does Not Impact Overall Survival: A National Cancer Database Analysis.

BACKGROUND: Recent trials established safety of axillary lymph node dissection (ALND) omission in patients with 1-2 positive lymph nodes (LN) on sentinel LN biopsy (SLNB). However, the benefit of ALND in patients with 3-5 positive LNs remains debated. We examined national trends of ALND versus SLNB in this subgroup and evaluated survival outcomes. PATIENTS AND METHODS: Using the National Cancer Database, we identified patients with pT0-2 ER+/HER2- breast cancer with 3-5 positive LNs who underwent adjuvant chemotherapy, endocrine therapy, and radiation therapy from January 2012 to December 2020. We compared patients who had SLNB alone versus ALND ± SLNB RESULTS: Among 13,270 patients, 1712 (12.9%) had SLNB and 11,558 (87.1%) had ALND. ALND rates decreased by 18.3% during the study period (93.4% to 75.1%). Compared with ALND, SLNB group had higher proportion of three positive LNs (63.1% versus 43.1%, p < 0.001), Charlson Comorbidity Index 0 (87.4% versus 84.4%, p = 0.001), pT1 tumor (42.8% versus 35.4%, p < 0.001), well-to-moderately differentiated tumor (72% versus 66.9%, p < 0.001), absence of lymphovascular invasion (42.7% versus 36.3%, p < 0.001), and lobular histology (16.5% versus 12.7%, p < 0.001). There was no difference in overall survival (OS) between SLNB and ALND in univariate or multivariable models (adjusted HR 1.0, p = 0.77). CONCLUSIONS: National rates for ALND decreased in patients with 3-5 positive LNs over the last decade. There was no difference in OS with omission of ALND in patients with ER+/HER2- breast cancer with 3-5 positive LNs, supporting further studies to evaluate deescalation of axillary surgery in this population.