Accuracy of the combination of mammography and sonography in predicting tumor response in breast cancer patients after neoadjuvant chemotherapy

Background: Residual tumor size after neoadjuvant chemotherapy is an important consideration in surgical planning. We examined the accuracy of the combination of mammography and sonography in predicting pathologic residual tumor size. Methods: Tumor size was evaluated by physical examination, mammography, and sonography at diagnosis and before surgery in 162 breast cancer patients who received neoadjuvant chemotherapy. Agreement between the predicted and the pathologic responses and the predicted and the pathologic tumor sizes was calculated. The effect of invasive lobular carcinoma, high nuclear grade, hormone receptor positivity, and the presence of an extensive intraductal component on the accuracy of mammography and sonography in predicting pathologic residual tumor size was analyzed. Results: Forty-two patients (25.9%) had a pathologic complete response (pCR). Overall agreement between predicted and pathologic responses was 53% for physical examination, 67% for mammography plus sonography, and 63% for physical examination plus mammography and sonography. The sensitivity of mammography and sonography in predicting pCR was 78.6%, and the specificity was 92.5%; the accuracy was 88.9%. Residual tumor size determined by mammography and sonography correlated with pathologic residual tumor size (r = .662); pathologic tumor size was within .5 cm of predicted in 69.1% of patients. Multivariate analysis showed that pathologic residual tumor size was underestimated for lobular carcinoma and overestimated for poorly differentiated tumors. Conclusions: The combination of mammography and sonography has a high accuracy in predicting pCR after neoadjuvant chemotherapy. Agreement of residual tumor size in mammography and sonography with pathologic residual tumor size was moderate.