Neoadjuvant Treatment in Patients with HER2-Positive Breast Cancer

Approximately 20%-25% of patients with breast cancer demonstrate amplification of the human epidermal receptor type 2 (HER2) gene, resulting in an overexpression of the HER2 receptor. This overexpression is associated with aggressive disease, relatively poor prognosis, and worse clinical outcomes. Neoadjuvant therapy is the standard treatment in patients with locally advanced, inflammatory, or inoperable primary breast cancer. It is generally used to downstage the tumors and therefore to improve surgical options including breast-conserving surgery rather than mastectomy. It has been confirmed that patients with pathological complete response (pCR) to neoadjuvant treatment have better disease-free survival (DFS) and overall survival (OS). Neoadjuvant treatment can also serve as in vivo test of sensitivity to the used therapeutic regimen. The preferred neoadjuvant approach to patients with HER2-positive breast cancer is a sequential anthracycline-taxane-based chemotherapy in combination with trastuzumab. Addition of other anti-HER2 agents has increased pCR rate up to 75% and will probably become a new therapeutic direction. In the first part of this paper, we summarize the information about HER2-positive breast cancer, the various treatment possibilities, and the results of the major neoadjuvant trials. The second part focuses on the data concerning the importance of pCR and the potential risk of cardiotoxicity associated with this treatment.