Sentinel lymph node biopsy before versus after neoadjuvant chemotherapy for breast cancer

Axillary lymph node status is the most important prognostic factor in the treatment of breast cancer. In recent years, sentinel lymph node biopsy (SLNB) has replaced conventional axillary lymph node dissection for predicting axillary lymph node status with higher accuracy. Moreover, neoadjuvant chemotherapy (NAC) is being used increasingly to treat not only patients with locally advanced inoperative breast cancer, but also those with initially operable breast cancer. The application of SLNB has now expanded to include this patient population, who were not previously considered good candidates for SLNB. A number of recent studies have evaluated the feasibility and accuracy of SLNB after NAC in breast cancer patients. Moreover, SLNB has been shown to be accurate in patients scheduled to receive NAC, and repeat SLNB has been performed after NAC for patients with positive nodes detected by the initial SLNB before NAC. Thus, the optimal timing of SLNB for patients with breast cancer in the neoadjuvant setting remains controversial. This article reviews the issues surrounding SLNB before vs. after NAC, according to the published literature and our experience.