Effect of neoadjuvant chemotherapy on lymphatic pathways leading to sentinel lymph nodes in breast cancer

Neoadjuvant chemotherapy (NAC) has been the standard therapy for breast cancer; however, whether sentinel lymph node biopsy (SLNB) should be performed after NAC in clinically node-positive patients is controversial. The indocyanine green (ICG)-fluorescence SLNB method (ICG-SLNB) provides a high identification rate as well as the ability to visualize lymphatic pathways, and previous studies have investigated the lymphatic pathways to sentinel lymph nodes (sentinel lymphatic pathways) using ICG- fluorescence method.  In this study, we used ICG-SLNB to compare the sentinel lymphatic pathways before and after NAC to investigate whether they were affected by chemotherapy. Although the locations of the sentinel lymph nodes were unchanged, NAC did alter 42.8% of the sentinel lymphatic pathway routes. Our data indicate that SLNB after NAC can still detect the sentinel lymph nodes regardless of the presence or absence of metastasis. Since the false negative rates of SLNB after NAC for node-positive patients is higher than that for node-negative patients according to meta-analyses, further investigation is required to determine whether to perform SLNB after NAC for node-positive patients.