Axillary Ultrasound Improves Accuracy of SLN Surgery in Breast Cancer

Using postchemotherapy axillary ultrasound findings to select women with node-positive breast cancer for sentinel lymph node surgery enhances the accuracy of the latter

medwireNews: Combining axillary ultrasound with sentinel lymph node (SLN) surgery after neoadjuvant chemotherapy results in a lower false-negative rate than SLN surgery alone in women with node-positive breast cancer, US researchers report.

“This allows selection of patients at the greatest likelihood of complete nodal response and provides them the opportunity to avoid axillary dissection if two or more SLNs are resected and found to be negative”, write Judy Boughey, from Mayo Clinic in Rochester, Minnesota, and study co-authors in the Journal of Clinical Oncology.

This analysis included data from 470 women enrolled in the American College of Surgeons Oncology Group Z1071 phase II trial who fulfilled the eligibility criteria: presence of clinical N1 disease, surgical excision of at least two SLNs and availability of postchemotherapy axillary ultrasound data. Of these, 286 patients had residual nodal disease with 36 false–negative episodes, giving a false–negative rate of 12.6%.

As this false–negative rate was above the 10% cut-off defined as acceptable, the researchers proposed a selection strategy that incorporates ultrasound data, such that only women with normal nodes as assessed by axillary ultrasound would undergo SLN surgery, while those with suspicious nodes would be sent for axillary node dissection without prior SLN.

This, they calculated, would result in an “acceptable” false–negative rate of 9.8%.

When patients were stratified by the axillary ultrasound findings, the false–negative rate did not differ significantly between the 99 participants whose nodal status was classified as suspicious and the 187 who had normal nodes.

But the analysis of data from the 611 women with node-positive disease (either clinical stage N1 or N2) showed that patients with ultrasound-detected suspicious nodes were significantly more likely to have residual nodal disease than those thought to have normal nodes, at 71.8% versus 56.5%.

Women with abnormal ultrasound results also had a significantly greater nodal disease burden than those with normal nodes, with larger metastases (median 11.0 vs 6.5 mm) and a higher number of positive SLNs (34.5 vs 21.0%).

In an accompanying press release, lead author Judy Boughey said that the goal is to personalise surgical treatment based on a patient’s response to chemotherapeutic interventions.

She concluded: “Avoiding complete underarm lymph node removal when possible means fewer women will experience the complications that can accompany that surgery, and avoiding those side effects should also save health care costs.”

Reference

Boughey JC, Ballman KV, Hunt KK, et al. Axillary Ultrasound After Neoadjuvant Chemotherapy and Its Impact on Sentinel Lymph Node Surgery: Results From the American College of Surgeons Oncology Group Z1071 Trial (Alliance). J Clin Oncol 2015; Published online before print 2 February. doi:10.1200/JCO.2014.57.8401

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