The Clinical Relevance of Target Lymph Node Biopsy after Primary Systemic Therapy in Initially Node-Positive Breast Cancer Patients

SIMPLE SUMMARY: Currently, the optimal axillary surgical approach for breast cancer patients with initial node-positive disease and conversion to clinically node-negative status after primary systemic therapy is unclear. The aim of our study was to evaluate the clinical impact of removing the initially most suspicious, labeled axillary lymph node in addition to the sentinel lymph node. Metastatic target lymph nodes were found in five out of 63 patients (7.9%), while the sentinel lymph node was either tumor-free or not detected. The removal of the target lymph node influenced the adjuvant systemic therapy in only one case (1.6%). However, complete axillary dissection was indicated in all five cases. Furthermore, with fewer than three sentinel lymph nodes removed, the target lymph node reduced the false-negative rate to less than 10%. We therefore conclude that although the target lymph node has a minor impact on adjuvant systemic therapy, it is relevant for surgical axillary management. ABSTRACT: Purpose: To assess the impact of the removal of the target lymph node (TLN) on therapy after the completion of primary systemic therapy (PST) in initially node-positive breast cancer patients. Methods: Pooled data analysis of participants of the prospective CLIP- and TATTOO-study at the University of Rostock was performed. Results: A total of 75 patients were included; 63 of them (84.0%) converted to clinically node-negative after PST. Both TLN and sentinel lymph node (SLN) were identified in 41 patients (51.2%). In five out of 63 patients (7.9%), the TLN was metastatic after PST and the SLN was either tumor-free or not detected. Axillary lymph node dissection (ALND) was conducted in all five patients. In one patient, systemic therapy recommendation was influenced by the TLN; adjuvant radiotherapy was influenced by the TLN in zero patients. For patients with fewer than three removed SLNs, the FNR was 28.6% for the SLN biopsy alone and 7.1% for targeted axillary dissection (TAD). Conclusions: Removal of the TLN in addition to the SLN after PST has only minimal impact on the type of adjuvant systemic therapy and radiotherapy. However, the extent of axillary surgery was relevantly affected and FNR was improved by TAD.