Prediction of Axillary Lymph Node Metastasis in Invasive Breast Cancer by Sound Touch Elastography

The aims of this study were to investigate the value of sound touch elastography (STE) in predicting axillary lymph node metastasis (ALNM) in patients with invasive breast cancer (IBC) and to explore whether lysyl oxidase (LOX) is correlated with increasing stiffness and promotion of metastasis in IBC. A total of 142 lesions in 142 patients were assessed by STE. The STE values of IBCs in the two groups were compared and the best cutoff values for diagnosing ALNM determined. Immunohistochemistry was used to detect LOX expression. Collagen fiber and elastic fiber content was determined by Masson and Weigert elastic fiber staining. Correlation analyses were performed to identify the associations of the data. The optimal cutoff values of E_max (maximum stiffness value of the tumor) and S_max (maximum stiffness value of the shell) for predicting ALNM of IBC were 94.58 and 148.78 kPa. Immunohistochemistry and Masson and Weigert elastic fiber staining were performed on 67 samples. LOX expression and collagen volume fraction were significantly higher in the ALNM+ group than in the ALNM- group (p = 0.04 and 0.03), except for elastic fiber content (p = 0.628). Moreover, E_max, S_max and LOX expression were positively correlated with collagen volume fraction (r = 0.624, 0.512, and 0.533, respectively). E_max and S_max were found to be predictors for ALNM of IBC. STE could serve as a non-invasive method for assessing lymph node status before surgery. Overexpression of LOX and increased collagen fiber contributed to the increased stiffness in the lesions and metastases of IBC.