Abstract PS2-01-12: Evaluation of different methods of targeting axillary lymph node for axillary surgery in patients with clinically node-positive breast cancer: A retrospective multicenter study

Abstract Background: In patients with clinically node-positive breast cancer undergoing chemotherapy, sentinel lymph node biopsy has been associated with a false-negative rate up to 14% according to previous studies. However, when target axillary dissection techniques, such as the placement of clips or markers in biopsy-proven metastatic lymph nodes, are employed, false-negative rates have been reported to decrease dramatically to approximately 1.4%, as shown in a pivotal study published in 2016. Despite this evidence, there has been no large-scale evaluation of axillary lymph node targeting methods in Korean clinical setting. This study aims to establish foundational data for targeted axillary strategies in Korea by comparing different localization methods used in patients with initially node-positive breast cancer. Methods: This study was conducted as a retrospective multicenter study involving patients with biopsy-proven node-positive breast cancer, who underwent surgery between January 2015 and June 2024. Patients were enrolled from seven institutions based on the following inclusion criteria; primary unilateral breast cancer, clinical tumor stage cT1-T4, biopsy-proven metastatic axillary lymph node with marker placement, and age over 18 years. Detailed analyses were conducted regarding the extent of axillary surgery, the type of marker used (clip or tattoo), and the use of localization techniques such as wire localization. Results: A total of 331 patients were included and the mean age was 49.3 years with 31 months of median follow-up. According to marking methods, targeted lymph nodes were successfully identified in 127 out of 145 patients (87.6%) who received clip markers, and in 178 out of 184 patients (96.7%) who underwent tattoo marking. There were no significant differences in concordance between sentinel lymph node and targeted lymph node across the clip and tattoo group (66.2% vs. 79.3%, p=0.298). Discordance between the sentinel lymph node and targeted lymph node was observed in 12.1% of total patients, 13.8% of patients in the clip marker group and 10.9% in the tattoo marker group. Among the clip group, patients who underwent wire localization showed a non-significant trend toward lower concordance between sentinel lymph node and targeted lymph node compared to those without wire localization (66.7% vs. 83.3%, p=0.069). Demographics and treatment characteristics, including tumor stage, surgery type, and systemic therapy, did not differ significantly between different markers. Conclusions: This is the first multicenter analysis in Korea focusing on targeting methods for metastatic axillary lymph nodes. No significant difference was observed in sentinel lymph node-targeted lymph node concordance and targeted lymph node detection between the clip and tattoo marker groups, suggesting that both methods have comparable feasibility in planning targeted axillary surgery. Interestingly, tattoo-based marking was used at a frequency comparable to clip marking, which contrasts with global trends. This may be attributed to the limited use of clip markers in Korea due to reimbursement restrictions. Also, these findings are clinically meaningful when considered in the context of the well-established false-negative rate of approximately 14% reported in node-positive breast cancer patients undergoing sentinel lymph node biopsy, suggesting that appropriate lymph node targeting strategies may help reduce discordance and improve surgical accuracy. Citation Format: C. Lee, J. Ryu, S. Ahn, J. Lee, H. Shin, J. Lee, Y. Kwak, H. Lee, S. Nam, S. Kim, J. Lee, J. Yu, B. Chae, S. Lee, W. Park, K. Kim, S. Lee. Evaluation of different methods of targeting axillary lymph node for axillary surgery in patients with clinically node-positive breast cancer: A retrospective multicenter study abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS2-01-12.