Contrast-Enhanced Ultrasound Biopsy of Sentinel Lymph Nodes in Patients with Breast Cancer: Implications for Axillary Metastases and Conservation.

BACKGROUND: In breast cancer patients, sentinel lymph nodes (SLN) can be identified in the breast clinic using contrast-enhanced ultrasound (CEUS). This study aimed to characterize and compare the extent of axillary metastases in patients with either a benign or malignant SLN core biopsy at the end of surgical treatment.
METHODS: Between 2009 and 2014, prospective data were collected on consecutive patients who underwent targeted core biopsy of SLN identified using CEUS in the breast clinic. Patients with abnormal lymph nodes (LN) detected on grey-scale ultrasound were not included. Patients whose initial SLN core biopsy was benign were compared with those who had a malignant SLN core biopsy.
RESULTS: 555 patients with invasive breast cancer had SLN successfully identified and core biopsied. 487 had a benign SLN core biopsy and 427 (88 %) did not have metastases found in surgically excised SLN. Only 2 % of patients with an initial benign SLN core biopsy were found to have 2 or more LN macrometastases. 68 patients had a malignant SLN core biopsy and 52 % had 2 or more LN macrometastases. The total volume of LN metastases was higher in the group of patients who had an initial malignant SLN core biopsy (P < 0.001).
CONCLUSIONS: Patients with a normal grey-scale ultrasound and benign SLN core biopsy are unlikely to have extensive axillary disease and may be ideally suited for axillary conservation. The decision to omit axillary LN dissection for patients with a malignant SLN core biopsy must be carefully considered because many will have undetected high-volume metastases.