New aromatase inhibitors in the treatment of advanced breast cancer.

New aromatase inhibitors are an exciting treatment option for postmenopausal women with hormone sensitive breast cancer. They have been shown to reduce tumors in a significant number of patients, and exhibit definite antitumor activity at a relatively low daily dose, and are highly potent, highly selective, and well-tolerated. Results from recent clinical phase III studies have confirmed their efficacy and the key role they have in the therapy for advanced breast cancer in postmenopausal women. The agents available for clinical use are: letrozole, anastrozole, and exemestane. These drugs have demonstrated high activity in women failing tamoxifen in locally advanced or metastatic disease. This communication reviews the clinical use of aromatase inhibitors, particularly in second and first line hormonal treatment of advanced breast cancer.