Second-look axillary ultrasound after breast MRI for enhanced preoperative nodal staging in newly diagnosed breast cancer patients.

Abstract

98 Background: Concomitant with widespread adoption of axillary ultrasound (AUS) with ultrasound-guided needle biopsy (USNB) of suspicious lymph nodes (LN) for preoperative nodal staging of breast cancer patients, utilization of breast MRI, which includes axillary imaging, has increased. Little is known about the added value of MRI imaging of the axilla in this context. We undertook this study to assess the role of breast MRI in preoperative axillary nodal staging. Methods: We studied 988 consecutive invasive breast cancers in patients undergoing primary operation including axillary surgery, without neoadjuvant therapy, from 2010-2011. Results: 505 patients (51%) underwent MRI of which 168 (33%) demonstrated suspicious findings in the axilla. Abnormal axillary MRI findings included cortical thickening, edema, enhancement, hilar effacement, and/or altered shape and size. 114 patients had findings concordant with AUS. 54 patients had suspicious LNs on MRI either without a preceding AUS (33 cases) or after an initially negative AUS (21 cases). Second look AUS was performed in 29 of these cases and was abnormal in 3 (10%) in whom USNB confirmed metastatic adenopathy. Of the 54 cases with MRI-detected suspicious LNs 20 (37%) were node positive at operation with a pN stage of N0 (63%), N0i+ (5%), N1mic (4%), N1 (20%), N2 (6%), N3 (2%); extranodal extension was seen in 7 of 20 node-positive patients (35%). Conclusions: Second look AUS, when performed secondary to suspicious axillary MRI findings, identified LN metastasis preoperatively in 10% of patients. When MRI is done to evaluate the breast in newly diagnosed breast cancer patients, axillary findings can enhance the accuracy of preoperative nodal staging. We recommend second look AUS when MRI demonstrates suspicious axillary LN findings. [Table: see text]