Sonographic features of benign and malignant axillary nodes post‐neoadjuvant chemotherapy

The aim was to determine whether sonographic features of metastatic axillary lymph nodes predict pathologic nodal status post-neoadjuvant chemotherapy (NCT) and help to tailor less invasive surgical management of the axilla. Patients with biopsy-proven cN1 primary breast malignancy who received NCT between January 2011 and December 2014 and had performed ultrasound were included in this study. Sonographic features of biopsy-proven clipped metastatic axillary nodes pre- and post-NCT were retrospectively reviewed by two independent readers. Changes in lymph node shape, fatty hilum status, cortical thickness, and cortical echogenicity were compared in patients with and without nodal pathologic complete response (pCR) using univariate and multivariate logistic regression models. Inter-reader variation was analyzed to determine the reproducibility of data. Of the 195 patients included in the study, 75 (45%) showed nodal pCR and 90 (55%) persistent metastatic disease post-NCT. pCR was significantly more likely in lymph nodes with isoechoic or hypoechoic cortical echogenicity post-NCT, (P = .02), conversion to normal cortical thickness (P = .0001), and oval shape (odds ratio = 0.17, P = .004), compared to lymph nodes with anechoic cortical echogenicity, persistent or diffuse cortical thickening, and irregular shape, respectively. The overall accuracy of sonographic nodal features in the prediction of pCR was 65% (95% CI: 58%-72%). The overall accuracy of sonographic features of biopsy-proven metastatic axillary lymph nodes post-NCT is not sufficiently high to predict pCR of axillary nodal status and thereby should not be solely used in guiding less invasive surgical approaches to the axilla.