Differences in axillary ultrasound protocols among prospective de-escalating axillary surgical staging trials in clinically node negative early breast cancer patients

•Prospective trials investigate de-escalating axillary surgical staging in cT1-2 N0 breast cancer.•Axillary ultrasound (US) protocols do differ among these prospective trials.•Uniformity in axillary US is required to improve extrapolation of the trial results. Surgical axillary staging of the axilla is a topic of debate regarding the potential of de-escalation in clinically node negative (cN0) early breast cancer patients treated with breast-conserving therapy. Axillary ultrasound is important to determine clinical nodal status. The aim of the current narrative review is to provide an overview of prospective trials on de-escalating axillary surgical staging in cN0 early breast cancer patients, with an emphasis on axillary ultrasound protocols. This narrative review provides an overview of the prospective de-escalating axillary surgical staging trials, in terms of comparing sentinel lymph node biopsy (SLNB) versus complete omission of SLNB, in cT1/2N0 patients treated with breast-conserving therapy. Information from each trial was collected, including reported axillary ultrasound protocols (including cortical thickness cut-off value) and axillary ultrasound-guided biopsy technique (fine-needle aspiration or core-needle biopsy). There is one recently published prospective trial and three ongoing prospective trials within the topic of this narrative review. Number of included patients in these trials ranges from 1405 to 5505 patients. The included trials differed whether or not to include patients with suspicious axillary ultrasound findings and a negative ultrasound-guided biopsy. Cortical thickness cut-off value ranged from 2.3 mm to 3.0 mm. Different ultrasound-guided biopsy techniques were performed among the included trials. Prospective de-escalating axillary surgical staging trials in clinically node negative early breast cancer patients treated with breast-conserving therapy do report differences in terms of axillary ultrasound protocols and ultrasound-guided biopsy techniques. Axillary ultrasound protocols do require uniformity in order to improve extrapolation of these trial results.