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

Background: 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. Methods: 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. Results: 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. Conclusion: 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.