Early assessment of shear wave elastography parameters foresees the response to neoadjuvant chemotherapy in patients with invasive breast cancer

Background: Early prediction of tumor response to neoadjuvant chemotherapy (NACT) is crucial for optimal treatment and improved outcome in breast cancer patients. The purpose of this study is to investigate the role of shear wave elastography (SWE) for early assessment of response to NACT in patients with invasive breast cancer. Methods: In a prospective study, 62 patients with biopsy-proven invasive breast cancer were enrolled. Three SWE studies were conducted on each patient: before, at mid-course, and after NACT but before surgery. A new parameter, mass characteristic frequency (f_mass), along with SWE measurements and mass size was obtained from each SWE study visit. The clinical biomarkers were acquired from the pre-NACT core-needle biopsy. The efficacy of different models, generated with the leave-one-out cross-validation, in predicting response to NACT was shown by the area under the receiver operating characteristic curve and the corresponding sensitivity and specificity. Results: A significant difference was found for SWE parameters measured before, at mid-course, and after NACT between the responders and non-responders. The combination of E_mean2 and mass size (s₂) gave an AUC of 0.75 (0.95 CI 0.62–0.88). For the ER+ tumors, the combination of E_{mean_ratio1}, s₁, and Ki-67 index gave an improved AUC of 0.84 (0.95 CI 0.65–0.96). For responders, f_mass was significantly higher during the third visit. Conclusions: Our study findings highlight the value of SWE estimation in the mid-course of NACT for the early prediction of treatment response. For ER+ tumors, the addition of Ki-67improves the predictive power of SWE. Moreover, f_mass is presented as a new marker in predicting the endpoint of NACT in responders.