The Validity of MRI in Evaluation of Tumor Response to Neoadjuvant Chemotherapy in Locally Advanced Breast Cancer

Background: Physical Examination (PE) and breast MRI are two of the current methods which have usually used in diagnosis of primary breast cancer. Their accuracy in detection of: either complete response or presence of residual tumor, however, has not yet been established in patients who have been received Neoadjuvant Chemotherapy (NAC). The purpose of this study was to evaluate the diagnostic accuracy of breast MRI in assessment of residual neoplastic tissue after NAC in patients with Locally Advanced Breast Cancer (LABC).

Methods: Twenty patients with LABC have undergone contrast-enhanced MRI before and after the NAC. Considering histology as the gold standard, the tumor sizes in MRI and PE have compared with the histology results. We have calculated for all below: the accuracy, sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) for each of MRI and physical examination, as well as Pearson's correlation coefficients between the results of MRI and PE, and their histology results.

Results: We have found an accuracy of 85% for MRI with a sensitivity of 100%, a specificity of 50%, a PPV of 83.3%, and an NPV of 100%. In addition, the accuracy for PE was 70% with a sensitivity of 71.4%, a specificity of 66.6%, a PPV of 83.3%, and an NPV of 50%. In this study, the calculated Pearson's correlation coefficient for MRI and histology was 0.817 (p<0.0001) versus 0.26 (p=0.26) for correlation between PE and histology.

Conclusion: MRI has higher sensitivity but less specificity than PE for detection of residual tumor after NAC in locally advanced breast carcinoma. Also, the tumor size that has measured by MRI had highly correlation with the histology.