1096 – Oncological safety of sentinel lymph node biopsy with single mapping tracer in cN+/ypN0 breast cancer women post-neoadjuvant chemotherapy: a real-world data study

Abstract

Introduction: Sentinel lymph node biopsy (SLNB) safety after neoadjuvant therapy in initially node-positive (cN+) breast
cancer remains controversial. Additionally, evidence regarding the use of a single mapping tracer in this setting is limited.
Methods: Women with non-metastatic cT1–3 cN0–cN2 breast cancer who were treated with neoadjuvant therapy
between 2011 and 2018 at a Brazilian tertiary hospital were retrospectively included. Axillary stage was clinically defined.
Clinicopathological characteristics and follow-up data (February 2022–November 2025) were analyzed.
Results: A total of 616 patients were included, with a mean age of 50.1 years (standard deviation ±11.2 years) and median
follow-up of 69.1 months; 322 were cN+. The cN+ group had more grade 3 tumors (44.4%; p=0.04) and more advanced T
stage (p<0.001); 103 underwent SLNB (92% using a single tracer), with a nodal downstaging rate of 45%. Axillary lymph
node dissection was performed in 37 cases. In the cN0 group, 257 patients underwent SLNB (96% with a single tracer).
Axillary recurrence rates after SLNB were comparable between the cN+ and cN0 groups (3% versus 2%; p=0.63). In the
whole cohort, 72-month overall survival (OS) was 81.7% and disease-free survival (DFS) was 74.3%. In ypN0 women, SLNB
demonstrated similar OS and DFS compared to axillary lymph node dissection (p=0.619 and p=0.849 for cN0; p=0.556 and
p=0.903 for cN+), regardless of the initial axillary status (p=0.873 and p=0.285). Furthermore, there were no differences in
OS or DFS regarding the number of lymph nodes dissected at SLNB (1–2 versus ≥3) in either the cN0 (p=0.546 and p=0.98)
or cN+ (p=0.122 and p=0.605) groups.
Conclusion: This real-world study suggests that there are no OS/DFS implications for ypN0 patients who undergo SLNB,
after neoadjuvant therapy. Also, it seems that dissecting in excess of two lymph nodes yields no additional benefits.
Importantly, these findings were obtained using a single mapping SLNB technique.
Ethics: Research Ethics Committee Approval (CAAE: 52444121.0.0000.5404).