Exemestane in early breast cancer: a review

Michael Untch¹, Christian Jackisch²

¹Interdisciplinary Breast Centre, Helios Klinikum Berlin-Buch, University Charité, Berlin, Germany; ²Department of Gynecology/Obstetrics, Klinikum Offenbach GmbH, Offenbach, Germany

Abstract: The adjuvant treatment of women with endocrine-sensitive early breast cancer has been dominated for the last 40 years by tamoxifen. However, the side-effects associated with this therapy have prompted a search for safer and biochemically more selective endocrine agents and led to the development of the third-generation aromatase inhibitors (AIs) anastrozole, letrozole and exemestane. Promising results in advanced disease have paved the way for treating early breast cancer, and AIs are increasingly replacing tamoxifen in the adjuvant setting. Several large, randomized trials with AIs have been completed or are ongoing in women with early-stage breast cancer, documenting the significant impact that these drugs are making on the risk for recurrence of breast cancer. As a result, there is increasing and widespread use of AI therapy for the treatment of early-stage endocrine-responsive breast cancer. This review summarizes the data for exemestane in the adjuvant setting, showing that a switch to exemestane after 2 to 3 years of tamoxifen therapy is associated with a statistically significant survival benefit and is regarded as being sensitive by international and national experts.

Keywords: early breast cancer, adjuvant setting, endocrine-sensitive, tamoxifen, aromatase inhibitor, exemestane, switch, IES 31, NSABP B-33, TEAM