Response assessment and follow-up by imaging in breast tumors

Primary systemic chemotherapy was first introduced for managing inoperable and large or locally advanced breast tumors (Bonadonna et al. 1995). It is also now used for operable tumors that would require mastectomy, trying to reduce tumor size and increase the rate of breast-conserving surgery (Avril et al. 2009). Thus, neoadjuvant chemotherapy (NAC) has become the standard treatment not only in patients with locally advanced breast cancer but also in patients with early invasive breast cancer in an attempt to downstage the primary cancer and to reduce micrometastases (You et al. 2015). Approximately 70% of patients demonstrate a clinical response either in physical examination or in anatomic imaging, but lastly, only 3–27% achieve a complete histopathologic response (van der Hage et al. 2001). For this reason, there is a need for accurate methods to monitor therapeutic effectiveness early during therapy (Avril et al. 2009).