Accuracy of ultrasonography and mammography in predicting pathologic response after neoadjuvant chemotherapy for breast cancer

Background: Neoadjuvant chemotherapy reduces tumor size before surgery in women with breast cancer. The aim of this study was to assess the ability of mammography and ultrasound to predict residual tumor size following neoadjuvant chemotherapy. Methods: In a retrospective review of consecutive breast cancer patients treated with neoadjuvant chemotherapy, residual tumor size estimated by diagnostic imaging was compared with residual tumor size determined by surgical pathology. Results: One hundred ninety-two patients with 196 primary breast cancers were studied. Of 104 tumors evaluated by both imaging modalities, ultrasound was able to size 91.3%, and mammography was able to size only 51.9% (χ² P < .001). Ultrasound also was more accurate than mammography in estimating residual tumor size (62 of 104 [59.6%] vs 33 of 104 [31.7%], P < .001). There was little difference in the ability of mammography and ultrasound to predict pathologic complete response (receiver operating characteristic, 0.741 vs 0.784). Conclusions: Breast ultrasound was more accurate than mammography in predicting residual tumor size following neoadjuvant chemotherapy. The likelihood of a complete pathologic response was 80% when both imaging modalities demonstrated no residual disease.