Objective To investigate the relationship between the expression of topoisomeraseⅡαin breast cancer patient and to evaluate the role of topoisomerase Ⅱα as a predictor of clinical response(CR and PR) after anthracycline-based chemotherapy for breast cancer.Methods forty-eight breast cancer patients receiving anthracycline-based neoadjuvant chemotherapy were restrospectively studied.Core biopsy samples before the chemotherapyand surgical samples were obtained for assay of topoisomerase Ⅱα expression.Results The expression of TopoⅡα decreased after chemotherapy.Overexpression of TopoⅡα before chemotherapy and the decreasing after chemotherapy was associated with better pathologic response.Conclusions We confirmed the predictive value of topoisomeraseIIα forclinical response after anthracycline-based chemotherapy.