Sentinel Lymph Node Biopsy after Neoadjuvant Chemotherapy in Primary Breast Cancer

Sentinel lymph node biopsy (SLNB) is the preferred axillary treatment in most cases of clinically axillary lymph node negative breast cancer. It consists of injection of a tracer, blue dye and/or radioactive colloid, in breast peri-areolar region (subareolar lymphatic plexus), tumor periphery, or tumor surgery bed. The tracer is then transferred through lymphatics to the first draining lymph nodes (LNs( in the axilla. These are detected by bluish discoloration when using blue dye, and by finding hot spots via a gamma camera held over injection site, and then on axilla if radioisotope mode.A large group of breast cancers that need neoadjuvant chemotherapy are those that have metastatic lymph node involvement. The neoadjuvant treatment might affect the nodes clinically. SLN used to be contraindicated at time of surgery in these cases in near past. However, recent studies have demonstrated safety of performing SLNB in lymph node positive breast cancers that become negative both in clinical exam and on ultrasound scan after neoadjuvant chemotherapy. Meanwhile, inflammatory breast cancer and locally advanced breast cancer with chest wall/ breast skin involvement are still absolute contraindications to SLNB.