Review of Novel Sentinel Lymph Node Biopsy Techniques in Breast Cancer Patients Treated With Neoadjuvant Chemotherapy.

Breast cancer patients who present with nodal metastasis receive neoadjuvant chemotherapy (NAC) with increasing frequency and can have complete pathologic response after treatment. In this clinical scenario, sentinel node mapping and biopsy are gaining acceptance instead of axillary dissection to avoid morbidity. Biopsy proven positive lymph nodes must be reliably excised and examined after NAC to further decrease the false negativity rate of sentinel lymph node (SLN) surgery. The standard method for axillary staging in breast cancer patients even after NAC is SLN biopsy (SLNB) with a radioisotope, blue dye, or both (dual technique). Currently, preoperative axillary staging with ultrasound and biopsy, along with placement of an image-detectable marker to be removed at the time of definitive surgery is recommended. In this study, we evaluated some methods of SLNB for patients treated with NAC like indocyanine green fluorescence, superparamagnetic iron oxide nanoparticles, indigocarmine blue dye, contrast-enhanced ultrasound using microbubbles, and tattooing. Some methods are also needed to ensure that the initially biopsy proven positive node is removed at the time of surgery to be carefully evaluated for residual disease after chemotherapy like clip placement to the suspected or involved nodes before NAC, and removing the clipped node with the guidance of 125I-labeled radioactive seed or guide wires.