The Emerging Role of Aromatase Inhibitors in the Adjuvant Management of Breast Cancer

Abstract

Adjuvant hormonal therapy for patients with endocrine sensitive breast cancer has been dominated for several decades by the gold standard tamoxifen. Promising data on third generation aromatase inhibitors (AI), anastrozole, letrozole and exemestane, in metastatic setting led to the development of these agents in early breast cancer. If recent results consistently show the superiority of these agents over tamoxifen, the therapeutic strategies of AIs in adjuvant setting remain discussed. Various approaches have been evaluated ranging from: 1. Front line 5 year use of AI instead of tamoxifen for newly diagnosed patients, to 2. Switching to AI after 2 or 3 years of tamoxifen for patients presently on tamoxifen (total of 5 years), or 3. Continuing with an AI after completion of 5 years of adjuvant tamoxifen. However, it is unclear today whether one of these AI strategies is superior to the other ones. The overall therapeutic index of AIs appears superior to that of tamoxifen with proven improved efficacy and better toxicity profile. AIs are all less toxic than tamoxifen in terms of thromboembolic disease and gynaecological complications while musculoskeletal disorders and joint pains are more frequent seen with AIs. This review will explore the results from the available adjuvant AIs trials and will define the present role of AIs in the adjuvant management of postmenopausal patients with breast cancer.