Imaging in Breast Cancer Patients Receiving Chemotherapy

Breast cancer is the second most common form of cancer in women and the most frequent cause of death. Despite breast screening programs, a substantial number of women are diagnosed with cancers greater than 2 cm in size or locally advanced disease, which is best treated with neoadjuvant chemotherapy (NAC) prior to surgery. Approximately 10% of women diagnosed with breast cancer annually will have locally advanced breast cancer, defined as stage III disease, where the cancer has either spread to regional lymph nodes and/or other tissue in the area of the breast, but not to distant sites. NAC offers the advantages of downstaging the disease, potentially reducing the extent of surgery. Presently, gadolinium enhanced MRI is the standard test used to monitor disease response to chemotherapy, and demonstrates changes in tumour size and extent between pre-NAC and post-NAC. Unfortunately, changes in tumour size may occur late in treatment regimen, thus producing false-negative results on early magnetic resonance imaging (MRI). Therefore, newer imaging techniques beyond anatomical imaging are needed to identify tumours that are unresponsive to chemotherapy and potentially change treatment plan early on to avoid significant morbidity associated with prolonged chemotherapy. A novel MRI technique utilizing hyperpolarized pyruvate has the potential to detect pathophysiological response early in the treatment regimen and would therefore allow for earlier identification of nonresponders and subsequent early modification of treatment regimens, if necessary.