Pathological findings of axillary dissection following positive sentinel lymph node biopsy in breast cancer patients undergoing upfront mastectomy (Poster presentation)

Abstract

<p>Background: The recently published SENOMAC and SINODAR-ONE trials offer new insights into the deescalation of axillary surgery for node-positive early breast cancer patients, including those who underwent mastectomy. This study aims to review the pathological findings from axillary dissection following the identification of positive sentinel lymph nodes in our mastectomy patients, and to evaluate the potential impact of applying the inclusion criteria from the SENOMAC trial.<br></p><p>Methods: This is a retrospective study involving breast cancer patients treated at our center between January 2019 and December 2023. We included all clinically node-negative breast cancer patients who underwent mastectomy and sentinel lymph node biopsy (SLNB), followed by axillary dissection due to a positive SLN on the frozen section. Exclusion criteria included patients with neoadjuvant treatment, recurrent breast cancer, and confirmed nodal involvement prior to surgery.<br></p><p>Result: 132 patients met our selection criteria. The median number of SLNs retrieved was 3 (range 1-17), with a median of 1 (range 1-9) positive SLNs. Completion of axillary dissection harvested additional metastatic lymph nodes in 45 patients (34.1%). Notably, 25 patients (18.9%) experienced a higher pathological N-stage after axillary dissection compared to SLNB alone. The extracapsular extension (p= 0.006) and T-staging (p= 0.002) were identified as predictors of residual metastatic lymph nodes following SLNB. We analyzed 113 patients who met the SENOMAC criteria (clinically node-negative T1-3 tumors with 1-2 macrometastases in SLNB). 30 (26.5%) had additional positive lymph nodes, with 16 (14.2%) experiencing nodal upstaging. Higher T-staging continued to be a significant predictor of additional positive nodes (p= 0.014).<br></p><p>Conclusions: Approximately one-third of patients with a positive SLNB exhibited additional metastatic lymph nodes upon axillary dissection, with 18.9% showing higher pathological nodal staging post-procedure. Local data on the long-term oncological safety of de-escalating axillary surgery in mastectomy patients are still pending, and optimal patient selection along with subsequent adjuvant treatment remains to be determined.<br></p>