Neoadjuvant endocrine therapy of breast cancer: which patients would benefit and what are the advantages?

Aromatase inhibitors (AIs) were more effective than tamoxifen as a neoadjuvant endocrine therapy (NAE) for postmenopausal women with estrogen receptor (ER)-positive breast cancer. Neoadjuvant AIs were shown to reduce tumor volume and to allow the performance of breast-conserving surgery (BCS) in cases that would normally require mastectomy. Predictive markers of neoadjuvant AIs may be ER-rich, progesterone receptor (PgR)-rich and human epidermal growth factor receptor 2 (HER2)-negative tumors. However, the ability of HER2 expression to predict a response to neoadjuvant AIs is controversial. Pathological tumor size, nodal status, Ki67 level, and ER score are predictive for the survival of postmenopausal women with breast cancer who have been treated with NAE. These factors could be useful in order to select patients who do not require chemotherapy. Indeed, neoadjuvant AIs are a potential treatment option for postmenopausal women with ER-rich breast cancer who prefer BCS despite having large tumors suitable for mastectomy.