Magnetic Resonance Imaging Evaluation of Pathological Response in Breast Cancer After Neoadjuvant Chemotherapy

Magnetic resonance imaging (MRI) is the most preferred radiological method in the evaluation of the response to neoadjuvant chemotherapy (NAC) in breast cancer. We aimed to evaluate the radiological and pathological correlation of the patients who were diagnosed with breast cancer by comparing taken MRIs before and after NAC to the pathological response. We also aimed to evaluate the pathological and radiological responses of the patients according to immunohistochemical and histopathological subtypes. Between June 2015 and January 2017, 45 women patients who took NAC for invasive breast cancer and who had a breast MRI before and after treatment were included in our study. While evaluating the NAC response of lesions, the longest diameter measure according to RECIST 1.1 criteria (Response Evaluation Criteria In Solid Tumors) and whether there is a presence of contrast or not were based on in the study. After NAC, we found with MRI 31.1% complete response, 62% partial response, and 6.7% stable disease. Between pathological response and MRI response was found a statistically significant relationship with the Mantel-Haenszel test (p: 0.003). The sensitivity of MRI was 83.3%, specificity 60%, positive predictive value 80.6%, and negative predictive value 64.3% in predicting pathological response. The diagnostic accuracy of MRI predicting pathological response was estimated to be 75.6%. Statistically significant-high Ki-67 levels were found in pathological complete responders in comparison with nonpathological complete responders (p: 0.001). In conclusion, dynamic contrast-enhanced breast MRI is an effective radiological method for determining the response to neoadjuvant chemotherapy when compared to post NAC histopathology as the gold standard.