Evaluation of Tumor Stiffness by Elastography Is Predictive for Pathologic Complete Response to Neoadjuvant Chemotherapy in Patients with Breast Cancer

Breast elastography (EG), which can objectively evaluate tumor stiffness, has been useful for differentiation of benign and malignant breast lesions. However, the value of EG for prediction of response to systemic therapy is poorly understood. The baseline evaluations of EG in 55 patients who received neoadjuvant chemotherapy were reviewed. We investigated the correlation between tumor stiffness and response to neoadjuvant chemotherapy. Tumor stiffness was evaluated by the Tsukuba elasticity scoring system. The mean EG scores were significant lower for the clinical and pathologic complete response (pCR) groups than for the others. When we categorized patients into two groups according to tumor stiffness, 26 patients were assigned to the low EG group (soft, scores from 1 to 3) and 29 patients were assigned to the high EG group (hard, score 4 and 5). The low EG group had significantly higher clinical complete response and pCR rates than the high EG group (clinical complete response, low EG group 38 % vs. high EG group 10 %, P = 0.024; pCR, low EG group 50 % vs. high EG group 14 %, P = 0.003, respectively). Furthermore, multivariate analysis indicated that estrogen receptor, human epidermal growth factor receptor 2, and low EG (odds ratio 13.04, 95 % confidence interval 1.19-458.28, P = 0.035) were independent predictive factors of pCR. Tumor stiffness evaluated by EG bears predictive potential for response to neoadjuvant chemotherapy. Stiffness evaluated by EG may be recognized as a clinically significant tumor characteristic, comparable to other data obtained by functional imaging techniques.