Background: The purpose of this study was to evaluate the value of quantitative shear wave elastography (SWE) in indicating the axillary lymph node metastasis (LNM) of invasive breast cancers (IBCs) and to investigate if S100A4 plays a key role in promoting metastasis and increasing stiffness in IBC.
Methods: The differences in SWE of 223 IBC patients were compared between the LNM+ and LNM- groups and the optimal cutoff values of SWE for diagnosing LNM were calculated. We searched the gene expression omnibus (GEO) to determine whether S100A4 was more highly expressed in IBCs that were LNM+ than in those that were LNM-. Sirius red and immunohistochemical staining were used to examine the collagen deposition and S100A4 expression of included tissue samples, and correlations of SWE and S100A4 expression with collagen deposition were analyzed.
Results: The optimal cutoff values for Emax (the maximum stiff value), Emean (the mean stiff value), and EmeanR (the ratio of Emean between mass and parenchyma) for diagnosing axillary LNM were 111.05 kPa, 79.80 kPa, and 6.89, respectively. GSE9893 exhibited more increased S100A4 expression in IBCs that were LNM+ than in those that were LNM-. Collagen volume fraction (CVF) and the average optical density of S100A4 (AODS100A4) in the LNM+ group were significantly higher than those in the LNM- group. Emax, Emean, EmeanR, and AODS100A4 were all positively correlated with CVF.
Conclusions: SWE in primary IBC could be useful for indicating axillary LNM. S100A4 may be a factor that regulates cancer-associated collagen deposition and metastasis; however, prospective molecular biological studies are needed.
Keywords: Invasive breast cancer (IBC); S100A4; collagen; lymph node metastasis (LNM); shear wave elastography (SWE).
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