Targeted axillary dissection after neoadjuvant chemotherapy for highly selective patients with initial cN1 breast cancer: A single-center prospective trial

Background: Sentinel lymph node (SLN) biopsy is gradually accepted as the standard of care in breast cancer patients with down-staged axillary disease after neoadjuvant chemotherapy (NAC). However, it is still difficult to precisely define pre-NAC clinical node-positive (cN1) and post-NAC clinical node-negative (ycN0). This prospective single-center trial was designed to evaluate the feasibility and accuracy of standard targeted axillary dissection (TAD) after NAC in highly selective pre-NAC cN1 patients (not considering ultrasound-based axillary ycN staging).Methods: This prospective trial included patients with initial pre-NAC cT1–3N1M0 invasive breast cancer but with a rigorous definition of cN1 from the Affiliated Cancer Hospital of Zhengzhou University. When NAC was effective (including complete and partial responses) and preoperative axillary palpation was negative, preoperative ultrasound-based axillary staging was not considered, and all patients underwent TAD followed by axillary lymph node (LN) dissection. The detection rate (DR) and false-negative rate (FNR) of TAD were calculated.Results: A total of 82 patients were included, and 77 of them were eligible for data analysis. The DR for TAD was 94.8% (73/77). There were 26 patients with one abnormal LN at the time of diagnosis based on ultrasound, 45 patients with two, and 2 patients with three. One patient had one TAD LN, four patients had two TAD LNs, and 68 patients had three or more TAD LNs. Preoperative axillary palpation yielded negative results for all 73 patients who successfully underwent TAD. Preoperative ultrasound-based ycN0 and ycN+ conditions were detected for 52 and 21 cases, respectively. The FNR was 7.4% (2/27) for standard TAD (≥3 SLNs), which was lower than that of all successful TAD (≥1 SLN; 10.0%, 3/30).Conclusions: In rigorously defined pre-NAC cN1 breast cancer patients, standard TAD is feasible for those with negative axillary palpation after NAC, and FNR is also less than 10%.Registration: chictr.org.cn, ChiCTR2100049093