Micrometastases in the sentinel node after neoadjuvant therapy. Is axillary dissection still required?

The present review intends to discuss the controversies and strengths in clinically node-positive patients with axillary nodal status ypN i+ / mi after neoadjuvant chemotherapy. Over the past 20 years, a de-escalation approach toward axillary surgery has been observed in patients with breast cancer. The worldwide use of sentinel node biopsy in the upfront setting and after primary systemic therapy substantially reduced surgical complications or late sequelae and eventually improving quality of life of patients. However, the role of axillary dissection is still unclear in patients with low residual disease post-chemotherapy, namely those with micrometastases in the sentinel node, and its prognostic role is still not very clear. The aim of the present narrative review is to report the available evidence on this topic, discussing the pros and cons of performing axillary lymph node dissection in the infrequent finding of micrometastases in the sentinel node after neoadjuvant chemotherapy. We will also describe the ongoing prospective studies which are expected to shed light and guide future decisions.