1080 - Residual Nodal Disease after Positive Sentinel Lymph Node Biopsy in Breast Cancer Patients Treated with Neoadjuvant Chemotherapy: Implication for Completion Dissection
Presenter(s)
T. Dvorak1, G. Castro2, M. Kahky2, C. King2, A. Nguyne2, P. Kelly1, R. Eisenberg2, J. Smith2, and D. Henry2; 1Department of Radiation Oncology, Orlando Health Cancer Institute, Orlando, FL, 2Orlando Health, Orlando, FL
Purpose/Objective(s): The optimal axillary surgical management of breast cancer patients who remain node-positive (ypN+) after neoadjuvant chemotherapy (NACT) with a positive sentinel lymph node (SLNB) is uncertain, awaiting results of the Alliance A011202 trial. While NCCN guidelines recommend completion dissection, some reports suggest risk-adapted approach. We sought to determine the incidence of residual nodal tumor burden at completion lymph node dissection (cLND) at our institution.
Materials/Methods: Retrospective analysis from a single-institutional cancer registry of breast cancer patients treated between 2014 and 2022, who underwent neoadjuvant chemotherapy, had a pathologically positive nodal involvement after neoadjuvant chemotherapy (ypN+) on sentinel lymph node biopsy, and underwent completion axillary dissection. We recorded the number of positive and total lymph nodes on the initial SLNB and on the cLND, including SLNB+ ratio, as well as size of nodal deposits and presence of extracapsular extension (ECE). Patients were stratified as having isolated tumors cells (“0i+”), micromet (“1mi”), 1 lymph node, 2 lymph node, 3 lymph node, and 4+ lymph nodes involved.
Results: There were 154 patients with ypN+ disease identified, 66 of whom had a positive SLNB, and underwent either concurrent or sequential cLND. Of these, 39% (26/66) had additional positive lymph nodes on cLND. Rates of additional positivity correlated with the amount of SLN involvement: 0% for those with 0i+ SLNs (n=1), 20% with micrometastases (n=5) or 1 positive SLN (n=30), 53% with 2 positive SLNs (n=19), 71% with 3 SLNs (n=7), and 100% with =4 SLNs (n=4). SLNB+ ratios of <0.4 had ~20% involvement, and ratios >0.4 had ~50% further involvement.
With increasing number of initially positive lymph nodes, the residual tumor burden increased, in terms of number of involved lymph nodes (average 2.6), LN tumor deposit size (average 5.4 mm), and presence of ECE (33%).Conclusion: The rate of further nodal involvement was 39%, a finding similar to the Alliance A011202 trial. Patients with low-volume and low-ratio sentinel nodal disease had a 20% rate, which rose to >50% with 2+ lymph nodes, supporting NCCN recommendation for completion dissection. In select cases with minimal sentinel nodal burden, the omission of CLND could be discussed with the patient and multidisciplinary team to balance reduced morbidity and residual disease impact. Further stratification, potentially including initial radiographic nodal burden and other characteristics, may be warranted to refine the selection criteria.
Abstract 1080 - Table 1| SLNB+ | Count | cLND- | cLND+ | % cLND Positive | Avg LN+ | Avg size (mm) | ECE+ |
| 0i+ | 1 | 1 | 0 | 0% | |||
| 1mi | 5 | 4 | 1 | 20% | 2.0 | 3.0 | 0% |
| 1 | 30 | 24 | 6 | 20% | 2.8 | 5.0 | 17% |
| 2 | 19 | 9 | 10 | 53% | 3.0 | 5.5 | 40% |
| 3 | 7 | 2 | 5 | 71% | 2.2 | 4.6 | 60% |
| 4+ | 4 | 0 | 4 | 100% | 3.2 | 8.7 | 50% |
| Total | 66 | 40 | 26 | 39% | 2.6 | 5.4 | 33% |