Response monitoring of breast cancer patientsreceiving neoadjuvant chemotherapy using breast MRI – a review of current knowledge

Background: Breast MRI is the most accurate method for evaluating treatment response in breast cancer patients receiving neoadjuvant chemotherapy (NAC). Methods: In this review, the current knowledge with respect to response monitoring of breast cancer patients receiving NAC using MRI is presented. Both standard and more advanced approaches are discussed, including potential pitfalls and future developments. Results: Many parameters have been proposed in the past for early response monitoring of NAC by MRI. Tumour size and volume, and apparent diffusion coefficient values seem most promising and are best validated. However, proper response criteria are still lacking. Breast MRI accuracy for pathologic complete response prediction has moderate sensitivity, but high specificity. Diffusion weighted MR imaging might be able to compensate this shortcoming. However, residual disease assessment after NAC is equally important. Studies have shown that assessment of residual disease by MRI is good, but can be influenced by several factors, such as breast cancer subtype or treatment regimen. Both overestimation and underestimation of residual disease by breast MRI have been reported, and both can have important clinical impact for the individual patient. Conclusion: MRI is the best imaging modality to monitor treatment response in breast cancer patients receiving NAC. However, further research is required to investigate potential confounding factors and its pitfalls.