The Z0011 Trial: Is this the end of axillary ultrasound in the pre-operative assessment of breast cancer patients?

Objectives The Z0011 trial questioned the role of axillary ultrasound (AxUS) in preoperative staging of breast cancer in patients with <= 2 positive sentinel lymph nodes (SLN). The purpose of this study was to correlate the number of abnormal nodes on AxUS with final nodal burden and determine the utility of AxUS with sampling (AxUS+S) in preoperative staging. Methods Six hundred and seventy-nine patients underwent pre-operative AxUS. Suspicious nodes were sampled. Negative axillae proceeded to SLN biopsy. The number of abnormal nodes identified on ultrasound and final histology as well as sensitivity and specificity for AxUS+S were calculated. Subgroup analysis was performed on Z0011 eligible patients. Results Two hundred and ninety-six patients had positive axillary nodes on final histology with 169 detected by AxUS+S (sensitivity 86.2 %, specificity 100 %, PPV 100 %, NPV 71.9 %). Patients with nodal metastases identified by AxUS had a mean burden of 7.3 nodes on histology (1 node on AxUS=5.2 nodes on histology, 2 nodes on AxUS=7.5 nodes, > 2 nodes=10.1 nodes). Patients diagnosed on SLNB had a mean burden of 2.2 nodes. Conclusion A single nodal metastasis detected on AxUS+S correlated with a mean of 5.2 nodes on final histology highlighting that AxUS remains essential in guiding appropriate management of the axilla in breast cancer.