Current and future roles of neoadjuvant chemotherapy in operable breast cancer.

Neoadjuvant chemotherapy was initially used only as treatment for locally advanced breast cancer. However, because breast cancer is considered to be a systemic disease in which distant micrometastases are already present at the time of the initial diagnosis, primary systemic therapy may be beneficial in the eradication of these micrometastatic lesions. Despite the fact that no survival benefit of neoadjuvant chemotherapy over adjuvant chemotherapy has yet been demonstrated, the clinical indication for neoadjuvant chemotherapy is being extended not only to stage T3/4 tumors but also to some stage T1/2 operable breast cancers. The current clinical benefits of the use of neoadjuvant chemotherapy are that (1) the safety of neoadjuvant chemotherapy is comparable with that of adjuvant chemotherapy, (2) neoadjuvant chemotherapy increases the possibility of the use of breast-conserving surgery, and (3) pathologic complete response may be a predictive indicator of better survival. Importantly, the response to neoadjuvant chemotherapy in vivo could provide a useful prediction of prognosis and help define strategies for an individual patient's future treatment with alternative chemotherapy regimens or molecular-targeting agents. Furthermore, the discovery of predictive markers for tumor response to neoadjuvant chemotherapy through the analysis of complementary DNA microarrays and proteomics may also help facilitate individualized chemotherapy, particularly by improving survival in patients with breast cancer with a poor prognosis. Herein we review the current status and future role of neoadjuvant chemotherapy in operable breast cancer in terms of its survival benefit and the potential for the individualization of adjuvant therapy for these patients.