Role of aromatase inhibitors in the upfront adjuvant hormonal therapy of postmenopausal patients with breast cancer.

Tamoxifen has been considered for several decades as the standard upfront hormonal therapy for patients with endocrine-sensitive early breast cancer. The efficacy and favorable toxicity profiles of third-generation aromatase inhibitors (AIs), anastrozole, letrozole and exemestane, in advanced disease led to their development in early breast cancer. Recent trial results consistently showed the superiority of AIs over tamoxifen in using the two following therapeutic approaches: either the upfront strategy (randomization of newly diagnosed patients: tamoxifen for 5 years vu AI for 5 years) or the sequencial strategy (randomization of newly diagnosed patients: tamoxifen (2-3 years) followed by AI or the inverse for a total of 5 years vs upfront AI for 5 years).Despite some common characteristics, a body of evidence on AIs suggests some specific differences between the three agents in terms of efficacy as well as toxicity profiles. Thus, these hormonal agents may not be considered interchangeable in clinical practice. This review will explore available results from AIs trials and will try to define their present role in the upfront adjuvant management of postmenopausal patients with breast cancer.