Aromatase inhibitors in early breast-cancer treatment: The story so far

Abstract

This paper describes the clinical evidence for using the aromatase inhibitors (AIs), anastrozole, letrozole and exemestane, as adjuvant therapy for postmenopausal women with early breast cancer. Efficacy data for AIs are reviewed across different treatment strategies (initial, switched, sequenced or extended adjuvant therapy). Although trials are still ongoing, AIs have demonstrated superiority over tamoxifen in terms of disease-free survival and recurrence as initial therapy, and benefits in overall survival in switched or extended strategies. However, comparisons of efficacy data across trials are confounded by methodological differences between trials. To address this problem, mathematical models have been developed which allow for inter-trial comparisons. Results from these models indicate that initial adjuvant therapy with an AI is superior to initial therapy with tamoxifen, and suggest that initial AI therapy is better than starting tamoxifen and then switching to an AI. Further clinical trials are needed to ascertain the optimal length of treatment with an AI.