Clipped lymph nodes for cN plus patients decrease false negative rate and lead to potential changes in surgical and oncological management after clinical complete response following neoadjuvant chemotherapy

Abstract Introduction Targeted axillary dissection (TAD) after neoadjuvant chemotherapy (NAC) is a new axillary staging technique that consists of surgical removal of biopsy-proven, positive, clipped axillary nodes (CLN) in addition to the sentinel lymph node biopsy (SLNB), and provides for more conservative axillary surgery1. A question was recently raised whether clipping a positive node for later assessment indeed leads to a management change2. The purpose of our study is to report the feasibility of TAD and to evaluate false negative rate (FNR), impact on surgical ad oncological management. Materials and methods This retrospective, single-institution, study included 73 consecutive women operated between 2019 and 2021 after NAC for cN+ disease confirmed by citology or histology, whose diseased lymph-node was marked with a clip before therapy. At surgery, in case of clinical-radiological complete response, patients underwent TAD (dual mapping with radiocolloid and blue dye + CLN) (n=43), or TAD plus ALND if any residual disease (n=30). The chemoterapeutsic regimen were antracycline/taxane based, with trastuzumab in case of HER2+ tumors. Patients were routinely evaluated with a breast MRI both before and after NAC. Results Clinical and pathological details of the 73 enrolled patients are listed in Table 1. The mean age at diagnosis was 49.53±10 years. Pathologic complete response was achievied in 32 out 73 patients (43.8%) with the greatest rate in HR-/HER2+ tumors (n=10/12; 83.3%). The identification rate of the CLN was 91.8% (68/73), and it was one of SLNs in 68.5% (50/73) of the cases. In cases in which one, two or three or more SLNs were identified, the CLN was in the SLN specimen in 42.9%, 77.8% and 81.8% of cases, respectively. The FNR of the SLN was 18.5% (CI: 4.9-38.1). In 18 cases the CLN was not in the SLN specimen; eleven out of 18 CLNs were positive, leading to ALND, and three of them had additional positive LNs. Only in one case the CLN was negative and the SLN was positive. In 3 cases (4.1%), the CLN was positive in the absence of residual tumour in the breast leading a potential change in the oncological management. Conclusions Removal of CLN after NAC is feasible, allowing de-escalation of surgical management of cN+ women in case of clinical-radiological complete response, as 59% of women avoided a formal ALND. The CLN coincides with SLN in about 70% of cases (more than 80% if three or more SLNs are identified) and reflects the overall status of the axilla in 97.3% of the cases. Adding CLN to SLNB contributes to reduce significantly the FNR of the latter from 18% to 0% (FNR for SLNB =18.5% vs FNR for TAD=0%). Potential changes in surgical (CLN+/SLNs-) and oncological management (CLN+/SLNs- and absence of residual tumor in breast) occurs in 15.1% (11/73) and 4.1% (3/73) of cases, respectively. References 1. Swarnkar PK et al. The Evolving Role of Marked Lymph Node Biopsy (MLNB) and Targeted Axillary Dissection (TAD) after Neoadjuvant Chemotherapy (NACT) for Node-Positive Breast Cancer: Systematic Review and Pooled Analysis. Cancers (Basel) 2021 Mar 26;13(7):1539. 2. Weiss A et al. How Often Does Retrieval of a Clipped Lymph Node Change Adjuvant Therapy Recommendations? A Prospective, Consecutive, Patient Cohort Study. 2022 Jun. Ann Surg Oncol 2022; 29(6): 3764-3771. Table 1: Clinicopathologic characteristics in the cN+ breast cancer patients NAC and clipped Lymph Node NAC Citation Format: Francesca Arienzo, Domenico Campagna, Paola Scavinia, Laura Broglia, Laura Broglia, Alessandra Ascarelli, Helena Colavito, Mirko Montanari, Elena Manna, Tiziana Mastropietro, Emanuele Zarba Meli, Massimo La Pinta, Daniela Musio, Mauro Minelli, Paola Scavina, Michelina Maria Carla Amato, Leopoldo Costarelli. Clipped lymph nodes for cN+ patients decrease false negative rate and lead to potential changes in surgical and oncological management after clinical complete response following neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-07-27.