Abstract:

Background and purpose: Multiple guidelines and consensus have confirmed the feasibility of sentinel lymph node biopsy (SLNB) after neoadjuvant therapy (NAT) in clinical nodal positive (cN⁺) patients converting to negative after NAT. There are few studies on the metastasis of axillary lymph node (ALN) at each anatomic level after NAT. This study aimed to explore the metastasis of ALN in each anatomic level, in order to provide more basis for the axillary de-escalation management after NAT. Methods: From April 2018 to 2020, 499 patients in Shandong Cancer Hospital were enrolled in this study. Patients (n=157) with initial cN⁺ and ycN₀ disease after NAT underwent SLNB plus axillary lymph node dissection (ALND). Patients (n=342) with initial cN⁺ and ycN⁺ disease after NAT had undergone ALND directly. At the same time, from May 2020 to December 2020, 46 patients with initial cN₁ and ycN₀ disease after NAT underwent targeted axillary dissection (TAD). These patients underwent clip insertion into the most suspicious ALN. Axillary surgery was performed with SLNB plus ALND. The ALN status at each anatomic level was analyzed. Results: Among the 499 patients, the incidence of ALN “skip metastasis” was 0.8% (4/499), similar to those patients without NAT, and it was 0.5% and 1.0% in SLNB group and directly ALND, respectively. Out of the sentinel lymph node (SLN)-positive patients after NAT, 41.4% of them had positive non-SLN (NSLN). Out of the SLN-negative patients after NAT, 10.1% of them had positive NSLNs, and the rates of positive NSLNs were 8.1% (5/62), 8.7% (2/23) and 21.3% (3/11) in cN₁, cN₂, and cN₃ subgroups, respectively. In the cN₁ subgroup, the NSLNs metastasis rate were 11.8% (4/34), 4.6% (1/22), and 0.0% (0/6) when patients had 1, 2, and 3 negative SLN, respectively. Among the 46 patients receiving TAD, if clips were inserted into the most suspicious ALNs and removed during surgery, the incidence of positive NSLN was 4.3% (2/46). The rates of positive NSLN were 5% (1/20), 5% (1/20), and 0% (0/6) when 1, 2, and 3 negative SLNs were detected, respectively, and it was not related to the number of detected negative SLN. Conclusion: ALND is still the standard axillary treatment in SLN-positive patients after NAT. For patient with initial cN₁ and ycN₀ disease after NAT, if clips were used to identify biopsied lymph nodes at diagnosis, the number of negative SLN might be no longer the requirement for SLNB to omit ALND after NAT.

Key words: Breast cancer, Neoadjuvant therapy, Sentinel lymph node biopsy, Targeted axillary dissection, Axillary lymph node