Neoadjuvant Therapy in Breast Cancer

Abstract

Neoadjuvant therapy (NAT), often referred to as primary therapy, is a wellestablished approach in the treatment of early breast cancer [1, 2]. Historically, NAT was initially used in women with locally advanced breast cancer. In this setting it represented the only chance for a patient with an otherwise inoperable cancer of the breast to obtain a tumor regression that made surgery feasible. These experiences in locally advanced tumors suggested that the primary breast cancers regressed frequently and, sometimes, became clinically undetectable during NAT. From locally advanced tumors, NAT was then studied in women with operable breast cancers, in whom it was speculated that anticancer treatment administered before surgery would offer a number of advantages compared to the traditional approach of surgery followed by adjuvant treatments. For example, in animal models, removal of the primary tumor was shown to have a permissive effect on distant micrometastases [3]; consequently, in the interval after breast surgery, micrometastases could grow to the extent that subsequent adjuvant treatments lost their efficacy. When potent chemotherapy agents such as the anthracyclines and, later, the taxanes became available, the rates of tumor regression observed in breast tumors were so impressive that NAT became synonymous with neoadjuvant chemotherapy (NAC).