The Evolving Role of Aromatase Inhibitors in Adjuvant Breast Cancer Therapy

The development of third-generation aromatase inhibitors (AIs) has brought about a major change in the therapeutic approach to patients with hormone-sensitive breast cancer. In randomized clinical trials, each of the third-generation AIs has demonstrated efficacy in the adjuvant treatment of postmenopausal women with receptor-positive tumors. Anastrozole has been shown to improve disease-free survival when compared with standard first-line tamoxifen, letrozole has been shown to further reduce the rate of breast cancer events when given as extended adjuvant therapy in women completing between 4.5 and 6 years of tamoxifen, and exemestane has been shown to improve disease-free survival when substituted for tamoxifen after an initial 2-3 years of adjuvant therapy. Although long-term follow-up for safety and overall survival continues in each of these trials, currently available data suggest that an AI should now be included as part of adjuvant endocrine therapy for the great majority of receptor-positive postmenopausal patients. To address these rapidly evolving issues related to the endocrine adjuvant treatment of postmenopausal women, an expert panel met in March 2004 in Hamburg, Germany, the site of the Fourth European Breast Cancer Conference. The panel's overview of recent endocrine data is presented along with updated results where available. In addition, case-based discussions are included to provide direction on how to integrate recent endocrine adjuvant clinical trial findings into everyday practice.