Assessment of the Impact of Chemotherapeutic‘Treatment Effect’ on Oncological Outcomes in InitiallyNode‐Positive Breast Cancer Patients UndergoingSentinel Lymph Node Biopsy Only After NeoadjuvantChemotherapy

ABSTRACT
Background: Sentinel lymph node biopsy (SLNB) is acceptable for patients who were initially node‐positive (cN+) and who achieve a complete radiological response after neoadjuvant chemotherapy (NACT). The impact of identifying chemotherapeutic ‘treatment effect’ (TE) in resected nodes on reducing false‐negative rates and oncological outcomes remains unclear. The aim of this study was to assess the impact of TE seen on SLNB and to determine oncological outcomes in this patient cohort.
Methods: cN+ breast cancer patients who received NACT and achieved nodal pathological complete response after SLNB only between 2014 and 2023 were assessed. Patients with negative SLNB (ypN0) were divided into two groups: (1) with TE and (2) without TE. Crude axillary recurrence rates were compared using the log‐rank test. Median disease‐free (DFS) and overall survival (OS) were compared using Kaplan−Meier curves.
Results: One hundred and fourteen patients were ypN0 after SLNB: 84 (73.7%) with TE and 30 (26.3%) without TE. Axillary recurrence trended towards a lower rate in those with TE (2.38% vs. 3.33%, p = 0.77). All patients with axillary recurrence had residual triple‐negative disease within the breast. There were no differences in median DFS (47.5 vs. 43.5 months, p = 0.91) and OS (53.5 vs. 44.5 months, p = 0.68) between the two groups, respectively.
Conclusion: Absence of TE in patients undergoing SLNB only does not appear to affect DFS and OS, but may increase the risk of axillary recurrence. Larger studies are needed to further determine the impact of TE on oncologic outcomes in these patients.