Preoperative neoadjuvant chemotherapy is essential for treatment of patients with breast cancer who have a large tumor mass and/or regional lymph node involvement, in terms of both tumor shrinkage and further improvement of the survival rate. In order to safely perform breast-conservation treatment for these patients, a detailed diagnostic procedure for precisely evaluating the therapeutic response is needed. Dynamic magnetic resonance imaging (MRI) is thought to be important in the evaluation of responses to neoadjuvant therapy in patients with considerably large tumors, however, few studies have detailed the changes, as depicted by dynamic MRI, that can be expected with neo-adjuvant chemotherapy. The purpose of this study was to document the changes that occur in response to neoadjuvant chemotherapy and to correlate them with the pathological findings observed in the surgical specimen. The study was performed at Kochi Medical School Hospital from 1995 to 1998. The series consisted of 31 patients with stage II and III breast cancer. Prior to and after 1-5 courses of neoadjuvant chemotherapy, dynamic MRI examinations were performed. Eight of the time-intensity curves for the 10 grade 1a tumors flattened during neoadjuvant chemotherapy, while two remained the same. Six of the curves flattened for the 14 grade 1b tumors, 7 remained the same, and one spiked. And for the seven grade 2 tumors, two of the curves flattened and five remained the same (p=0.0340). In the five grade 1 tumors, the mean after/before normalized peak signal intensity ratio was 0.42+/-0.22. In the 18 grade 2 and 8 grade 3 tumors, the mean normalized signal intensity ratios were 0.59+/-0.28, 0.88+/-0.10, respectively (p<0.05). In the 15 tumors that showed shrinkage of the linear enhancement during neo-adjuvant chemotherapy, 10 had no remarkable intraductal spreading and 9 had a negative surgical margin. In the 16 tumors that had no shrinkage of the linear enhancement during chemotherapy, 13 had remarkable intraductal spreading and 12 had a positive surgical margin (p<0.05). It is concluded that dynamic MRI is a valuable tool for determining tumor response and predicting a positive surgical margin. Breast-conservation treatment can be performed for these patients by meticulous assessment using such detailed diagnostic procedures after local tumor control by combined chemotherapy with high dose-intensity.

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