Examining the false-negative rate of a negative axillary node ultrasound-guided core needle biopsy in breast cancer patients undergoing upfront surgery

Axillary assessment in breast cancer is key to determining an upfront surgery or neoadjuvant chemotherapy (NAC) approach. We investigated the false-negative rate (FNR) of axillary-node ultrasound-guided core-needle biopsy (US-CNBx) and the surgical management of pN ​+ ​patients. This single-institution study from 2010 to 2020 included patients with benign findings on US-CNBx and upfront surgery. Statistical analyses were performed via t-tests and chi-squared tests. 95 axillae met inclusion, 23 were pN+, resulting in a US-CNBx FNR of 24.2 ​%. pN ​+ ​patients more frequently had cT2-T3 tumors vs pN0 patients (43.5 ​% vs 27.8 ​%, p ​= ​0.03). Of the 23 ​pN ​+ ​patients, 9 underwent breast-conserving surgery (BCS) and 14 underwent mastectomy. In those with BCS, 7 had 1–2 positive nodes, 2 had ≥3 nodes; 3 received an ALND. In those with mastectomies, 12 had 1–2 positive nodes, 2 had ≥3 positive nodes; 6 received an ALND. In this cohort, US-CNBx had a FNR of 24.2 ​%. pN ​+ ​patients had a greater frequency of cT2–cT3 tumors, therefore clinicians should be cognizant of potential occult nodal disease despite negative CNBx when deciding management. •US-CNBx had a false negative rate of 24.2% in women with invasive breast cancer who underwent upfront surgery.•Patients with pN ​+ ​disease had larger tumors compared to patients with pN- disease following negative US-CNBx.•Three pN+ ​patients had HER2+ tumors or TNBC and were eligible for NAC, however, they had upfront surgery.•Clinicians may suspect occult axillary disease in larger tumors when weighing upfront surgery vs NAC in HER2+ and TNBC.