Tumor reduction rate predicts early recurrence in patients with breast cancer failing to achieve complete response to primary chemotherapy

Background Primary chemotherapy (PCT) for breast cancer is effective as postoperative adjuvant therapy, which permits more lumpectomies and can be used to study breast cancer biology. Many reports indicate that the presence or absence of residual cancer after PCT has been proposed as a critical prognostic factor for prolonged disease-free and overall survival. However, pathological complete response (pCR) has not been obtained for all cases, and the majority of the patients indicate partial response to PCT. Methods The subjects consisted of 41 breast cancer patients failing to achieve a pCR to PCT. Enhanced MRI using a 1.5-T system was carried on just before chemotherapy induction and before surgery. The correlation between tumor reduction rate derived from MRI and occurrence of early events in breast cancer patients was analyzed retrospectively. Results In the median, 40 (23-48) months' follow-up, 14 recurrences and 7 deaths were observed. Disease-free cases had a greater tumor reduction rate than recurred cases (p = 0.0035). If the average of 56% was chosen as the cutoff value, the significant difference was found between the groups with high and low tumor reduction rates (p = 0.0036) with a hazard ratio 2.62. Moreover, cancer-associated deaths were often observed in the cases with the lower tumor reduction rate compared with alive patients (p = 0.0003). Conclusions The evaluation of tumor reduction rates on MRI was considered to be useful for predicting early outcome among breast cancer patients who cannot achieve pCR after PCT.