Early Evaluation of Relative Changes in Tumor Stiffness by Shear Wave Elastography Predicts the Response to Neoadjuvant Chemotherapy in Patients With Breast Cancer

Objectives-Neoadjuvant chemotherapy plays an important role in comprehensive therapy for breast cancer, but response prediction is imperfect. Shear wave elastography (SWE) is a novel technique that can quantitatively evaluate tissue stiffness. In this study, we sought to investigate the application value of SWE for early prediction of the response to neoadjuvant chemotherapy in patients with breast cancer. Methods-We prospectively evaluated tumor stiffness in 62 patients with breast cancer using SWE, which was performed at baseline and after the second cycle of neoadjuvant chemotherapy. After chemotherapy, all of the patients underwent surgery. We investigated the correlations between the relative changes in tumor stiffness (Delta stiffness) after 2 cycles of chemotherapy and the pathologic response to the therapy. Results-Compared with baseline values, tumor stiffness after 2 cycles of neoadjuvant chemotherapy was significantly decreased in responders (P <.001) but not in nonresponders (P=.172). The Delta stiffness was significantly higher in responders (-42.194%) than in nonresponders (-23.593%; P =.001). As determined at either the baseline or after the second cycle of chemotherapy, tumor stiffness was significantly lower in responders than in nonresponders (P =.033 and .009, respectively). The Delta stiffness threshold for distinguishing between responders and nonresponders was -36.1% (72.92% sensitivity and 85.71% specificity). Furthermore, correlating Delta stiffness with clinical and pathologic characteristics, we found that estrogen and progesterone receptor expression showed statistically significant correlations with Delta stiffness (estrogen receptor, P=.008; progesterone receptor, P =.023). Conclusions-Early evaluation of relative changes in tumor stiffness using SWE could effectively predict the response to neoadjuvant chemotherapy in patients with breast cancer and might indicate better therapeutic strategies on a timelier basis.