Correlation of shear-wave elastography parameters with the molecular subtype and axillary lymph node status in breast cancer

Purpose: To examine correlations between shear-wave elastography (SWE) parameters with molecular subtype and axillary lymph node (LN) status of breast cancer. Methods: We retrospectively analyzed 545 consecutive women (mean age, 52.7 & PLUSMN; 10.7 years; range, 26-83) with breast cancer who underwent preoperative breast ultrasound with SWE between December 2019 and January 2021. SWE parameters (Emax, Emean, and Eratio) and the histopathologic information from surgical specimens including histologic type, histologic grade, size of invasive cancer, hormone receptor and HER2 status, Ki-67 proliferation index, and axillary LN status were analyzed. The relationships between SWE parameters and his-topathologic findings were analyzed using an independent sample t-test, one-way ANOVA test with Tukey's post hoc test, and logistic regression analyses. Results: Higher stiffness values of SWE were associated with larger lesion size (>20 mm) on ultrasound, high histologic grade, larger invasive cancer size (>20 mm), high Ki-67, and axillary LN metastasis. Emax and Emean were the lowest in the luminal A-like subtype, and all three parameters were the highest in the triple-negative subtype. Lower value of Emax was independently associated with the luminal A-like subtype (P = 0.04). Higher value of Emean was independently associated with axillary LN metastasis for tumors & LE; 20 mm (P = 0.03). Conclusion: Increases in the tumor stiffness values on SWE were significantly associated with aggressive histo-pathologic features of breast cancer. Lower stiffness values were associated with the luminal A-like subtype, and tumors with higher stiffness values were associated with axillary LN metastasis in small breast cancers.