"Exemestane is the only anti-hormonal therapy that has been shown to demonstrate improved overall survival over tamoxifen alone," said Lead Investigator Professor Charles Coombes, director of cancer medicine, Imperial College, London. These significant survival benefits were seen in patients who are considered hormone sensitive, which represents 97% of the study population. Although not statistically significant in the intent to treat population, 15% of patients taking Aromasin were more likely to be alive versus those that continued on tamoxifen. These new findings were based on nearly 5 years of follow-up after randomization in the IES trial. IES was a large randomized double blind multinational trial of postmenopausal women with early breast cancer which was designed to compare the clinical benefits of switching 2352 patients to Aromasin after 2 to 3 years of tamoxifen versus continuing 2372 patients on tamoxifen for a full 5 years of therapy. The 5 year follow-up time includes a period of observation lasting over 2 years after completion of all treatment.
Earlier results of the IES trial, which led to US FDA and European regulatory approvals of Aromasin for treatment of early breast cancer, found that postmenopausal hormone receptor positive patients, which represented 85% of all patients in the trial, who switched to Aromasin reduced their risk of breast cancer recurring by 35% versus patients who stayed on tamoxifen for 5 years. At the earlier time point, a difference in overall survival had not been seen.
Breast cancer is one of the most comm