Omission of axillary sentinel lymph node biopsy in early invasive breast cancer

Local treatment of the axilla in clinically node-negative (cN0) early breast cancer patients with routine sentinel lymph node biopsy (SLNB) is debated after publication of ACOSOG Z0011 data in 2010. Currently, prospective randomized surgical trials investigating the omission of SLNB in upfront breast-conserving surgery (BCS) and in the neoadjuvant setting, respectively. Several prospective randomized trials (SOUND, INSEMA, BOOG 2013–08, and NAUTILUS) with axillary observation alone versus SLNB in cN0 patients and primary BCS have primary objectives to evaluate oncologic safety when omitting SLNB. The Italian SOUND trial was the earliest to open in 2012 and has completed accrual in 2017. First oncologic outcome data are expected soon for SOUND and at the end of 2024 for INSEMA. Improvements in systemic treatments for breast cancer have increased the rates of pathologic complete response (pCR) in patients receiving neoadjuvant systemic therapy (NAST), offering the opportunity to de-escalate surgery in patients who have a pCR. Two prospective single-arm trials (EUBREAST-01, ASICS) include only patients with the highest likelihood of having a pCR after NAST (triple-negative or HER2-positive breast cancer) and type of surgery will be defined according to the response to NAST rather than on the classical T and N status. The ongoing trials will hopefully help us to understand whether we might take the best therapeutic decisions without the pathologic evaluation of nodal status.