Neoadjuvant chemotherapy: early response as a guide for further treatment: clinical, radiological, and biological.

Neoadjuvant chemotherapy (NACT) was initially developed as a treatment strategy for patients with locally advanced breast cancer to improve operability and locoregional control. Today, NACT has become an equivalent option along with adjuvant treatment, and it is regarded as standard treatment approach for patients with locally advanced cancer because it enables breast-conserving therapy to these patients. In addition, there is increasing information on NACT in operable breast disease that supports its use in routine practice for operable tumor stages. According to the German S3 and AGO guidelines, NACT is indicated for every patient with breast cancer, who would need adjuvant chemotherapy after evaluation of radiological, histological, and clinical prognostic factors. Based on a broad range of clinical studies during the last 10 years, it has been demonstrated that NACT leads to an increasing rate of breast-conserving operations, reduced mortality, and less toxicity. A very important issue is to obtain early information about the responsiveness of the primary tumor to chemotherapy, so that individualized therapeutical strategies can be developed. The decision to proceed with NACT is depending on several considerations including surgical aspects, pretreatment diagnostic evaluations, and efficacy monitoring as well as biological aspects to predict response.