Preoperative Axillary US in Early-Stage Breast Cancer: Potential to Prevent Unnecessary Axillary Lymph Node Dissection.

Purpose To evaluate the value of preoperative axillary ultrasonography (US) for preventing unnecessary axillary lymph node dissection after sentinel lymph node (SLN) biopsy in a large series of patients with early-stage breast cancers treated with both breast-conserving surgery and SLN biopsy. Materials and Methods From March 2009 to February 2013, 1802 patients who underwent breast-conserving surgery for clinical T1-2/N0 cancers and SLN biopsy with or without axillary lymph node dissection were included. Preoperative axillary US results and clinical-pathologic variables were compared according to the status of non-SLN metastasis. Multivariate logistic regression analysis was performed to find factors associated with non-SLN metastasis. Results Of 1802 patients, 397 (22.0%) underwent axillary lymph node dissection due to positive SLN biopsy and 76 (4.2%) had non-SLN metastasis at final histopathologic examination. Patients with non-SLN metastasis were younger and showed positive axilla at US and clinical T2 stage more frequently (P < .05). At multivariate analysis, positive axilla at US (P = .001), clinical T2 stage (P = .005), and lymphovascular invasion (P < .001) were significantly associated with non-SLN metastasis. Among 1284 patients with negative axilla at US and clinical T1 stage cancer, 1254 (97.7%) did not have non-SLN metastasis and 30 (2.3%) had non-SLN metastasis. Conclusion Preoperative axillary US results and clinical T stage are associated with the status of non-SLN metastasis in patients with early breast cancer. The results of this study suggest that preoperative axillary US can help select patients at minimal risk of non-SLN metastasis, for whom axillary lymph node dissection can be omitted. RSNA, 2018 Online supplemental material is available for this article.