Management and Outcomes in Patients with Breast Cancer with 1-of-1 and 2-of-2 Positive Sentinel Nodes

Background: The ACOSOG-Z0011 and AMAROS trials showed that axillary lymph node dissection (ALND) provided no benefit for patients with 1–2 positive sentinel lymph nodes (+SLNs). There remains apprehension to omit ALND for patients in whom only 1–2 SLNs are retrieved and all are positive. This study evaluates current practices and pathological findings when ALND is pursued. Patients and Methods: We identified female patients with cT1–3N0 breast cancer who underwent sentinel lymphadenectomy from 2018 to 2021 in the National Cancer Database (NCDB). Patients with ≤ 2 SLNs were included and categorized on the basis of the number positive/removed: 0/1, 1/1, 1/2, and 2/2. We assessed the rates and factors associated with ALND. Results: A total of 102,802 patients were included: 0/1: 79,106 (77%), 1/1: 10,549 (10%), 1/2: 10,068 (10%), and 2/2: 3079 (3%). ALND was most frequently performed for patients with 2/2 +SLNs (41%), followed by 26% with 1/1 +SLNs, 19% with 1/2 +SLNs, and 6% with 0/1 +SLNs. On multivariable analysis, 2/2 +SLN status was the strongest independent predictor of ALND. For triple-negative and human epidermal growth factor receptor (HER)2+ patients, ALND did not affect adjuvant chemotherapy or radiation rates. Among pN+ hormone receptor (HR)+/HER2− patients > 50, ALND was linked to higher chemotherapy rates in all SLN groups, despite no difference in 21-gene recurrence scores. With a median follow-up of 35.4 months, ALND did not improve overall survival. Conclusions: ALND is being performed at higher-than-expected rates in patients with ≤ 2 +SLNs and may contribute to adjuvant overtreatment, particularly in HR+/HER2− patients. Multidisciplinary case discussions and ongoing provider education are essential to reduce unnecessary axillary interventions.