Abstract 87P
Background
Neoadjuvant systemic therapy (NST) is widely used in patients with breast cancer. Major advantages include locoregional response and adjustment of postneoadjuvant systemic therapy (PST). ALND remains the standard procedure for cN+ disease BC although deescalation of the axillary surgery has to be discussed in patients who convert from cN+ to ypN0.
Methods
Data from five certified german breast cancer centers in patients who received NST between 2018 and 2022 were analyzed in terms of locoregional response and type of axillary surgery after NST.
Results
Data from 720 patients were analyzed. 309 patients had cN+ and 377 patients had cN0 status before NST, respectively. Of the initial 309 cN+ patients, 203 had postneoadjuvant ycN0 status by imaging (US, MG, MRI). In 71 patients ( cN + and ycN0), the final histology showed pN+ status (ypN0i+ in 5, ypN1mi in 15, ypN1-3 in 51 patients). In 203 patients with initially cN+ and ycN0, the type of axillary surgery was: SLNB alone in 41 patients (5 patients with positive SN ; FNR 12.1%), in 72 patients targeted axillary dissection (TAD) ( ypN0 in 45 patients, 62.5%) and in 90 patients ALND ( ypN0 in 45 patients, 50%). Of 82 initially cN+ and postneoadjuvant ycN+ patients, 24 had ypN0; false positive rate (FPR) 29%. From 377 patients with cN0 and ycN0 in 34 patients final histology showed pN+ status (ypN0i+ in 6, ypN1mi in 8, ypN1-3 in 20 patients) corresponding to FNR of 9%.
Conclusions
Our results show that at in patients with cN0 status prior to NST, the false negative rate (ypN+) was 9%. In cN+ and postneoadjuvant ycN0 patients the FNR was 35%. Since the postneoadjuvant systemic and locoregional treatment crucially depend on the ypN status, the ALND ist still standard especially in patients who just clinically convert from cN+ to ycN0. The role of TAD is still under investigation.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.