Clinical Application of Multimodal Sentinel Lymph Node-Mapping Method for Patients with Breast Cancer Undergoing Neoadjuvant Chemotherapy: A Final Analysis.

Background: Neoadjuvant chemotherapy (NAC) leads to a nodal pathologic complete response (pCR) in approximately 70% of breast cancer patients, especially in human epidermal growth factor receptor 2 (HER2)-positive and triple-negative subtypes. However, sentinel lymph node (SLN)-mapping after NAC remains challenging due to lower identification and higher false-negative rates compared with early-stage breast cancer. This study aimed to evaluate the efficacy of a multimodal SLN-mapping approach after NAC.

Methods: This prospective, single-center, randomized controlled trial enrolled 270 patients with breast cancer receiving NAC between May 2021 and July 2024 and randomized them (1:1:1) to arm A (radioisotope [RI] + indocyanine green fluorescence [ICG-F]), arm B (RI + vital dye [indigo carmine]), and arm C (ICG-F + vital dye). The primary outcome of SLN-identification rate and the secondary outcome of SLN-operation time were analyzed.

Result: Interim results showed SLN-identification rates of 95% in arm A, 92% in arm B, and 79% in arm C, with a significant difference between arms A and C (0.1597; p = 0.0055). The final analysis comparing only arms A and B showed SLN-identification rates of 92.6% (100/108) and 90.6% (96/106), respectively (p = 0.2967), with a significantly shorter mean time to first SLN detection in arm B than in arm A (7 vs. 8 min; p = 0.0046). The intra-arm detection rates differed significantly: arm A (RI, 96.0%; ICG-F, 92.0%; p = 0.232) versus arm B (RI, 97.9%; vital dye, 72.9%; p < 0.0001).

Conclusion: Multimodal SLN-mapping demonstrated high post-NAC identification rates without significant intra-arm differences in the SLN-identification rates, whereas SLN-detection rates differed by the method for each arm. For patients with breast cancer, RI + ICG-F SLN-mapping is an effective dual-method post-NAC approach.