Dynamic contrast-enhanced MRI for monitoring response to neoadjuvant chemotherapy in breast cancer

The general aim of this thesis is to investigate the role of dynamic contrast-enhanced MRI in monitoring response of breast cancer during neoadjuvant chemotherapy. The role of MRI with respect to achieving personalized breast cancer treatment by improving response monitoring is examined.
Our findings demonstrate the potential clinical relevance of contrast-enhanced MRI for monitoring response of breast cancer during and after neoadjuvant chemotherapy. We defined MRI criteria ( reduction < 25% in largest diameter of late enhancement) to objectively switch the chemotherapy regimen in case of an ‘unfavorable’ response during neoadjuvant chemotherapy. We have demonstrated that during chemotherapy, MRI is effective in monitoring response in triple-negative and HER2-positive disease, but it is inaccurate in ER-positive/HER2-negative breast cancer.
After neoadjuvant chemotherapy, the tumor size at baseline MRI, the reduction in tumor size on MRI and breast cancer subtype should be taken into account to select patients for breast-conserving surgery. A radiological complete response on MRI after chemotherapy is associated with an excellent prognosis in ER-positive/HER2-negative breast cancer.
Based on the results of this thesis we recommend the use of MRI for the evaluation of response of breast cancer to neoadjuvant chemotherapy. Our results suggest that the performance of MRI in the assessment of response during and after neoadjuvant chemotherapy could be influenced by the breast cancer subtype. Although prospective and large validation studies are needed to confirm this finding, we believe that it is relevant to consider this finding if MRI is opted for evaluation of treatment response.