Can Axillary Ultrasound Identify Node Positive Patients Who can Avoid an Axillary Dissection After Neoadjuvant Chemotherapy?

Introduction: Axillary lymph node dissection (ALND) is recommended for patients with invasive breast cancer with axillary metastasis treated with neoadjuvant chemotherapy (NAC) who do not have a nodal pathologic complete response (n-pCR). We hypothesized that patients with a single, ultrasound-suspicious, nonpalpable lymph node (LN) at diagnosis, who do not achieve an n-pCR, will have ypN1 disease on surgical pathology.

Methods: This retrospective study identified breast cancer patients in our institution from 2012 to 2020 with axillary metastasis treated with NAC who did not achieve an n-pCR and had an ALND. Patient's tumor characteristics, axillary ultrasound, and lymph node disease burden at the time of surgery were reviewed.

Results: Fifty five patients met the criteria and 36% had one suspicious LN on ultrasound, 25% had 2, and 38% had >3. After chemotherapy, 64% had ypN1 disease, 29% had ypN2 disease, and 7% had ypN3 disease. Of the 20 patients with one abnormal LN on initial ultrasound, 17 (85%, 95% CI 61-96%) had ypN1 disease. Eleven patients with one abnormal LN on initial ultrasound also had no suspicious LNs on prechemotherapy physical exam; among these patients, 100% had ypN1 disease.

Conclusions: For breast cancer patients who do not achieve an n-pCR after NAC, pretreatment normal clinical axillary exam and prechemotherapy ultrasound showing only one abnormal LN is associated with ypN1 disease. It may be reasonable to consider omitting completion ALND in this subset of patients while awaiting the results of the Alliance A011202 trial.