Survival benefit maintained in long term follow-up study of Aromasin for early breast cancer patients

Pfizer announced new, longer-term data from the Intergroup Exemestane Study (IES) showing that women who switched to Aromasin (exemestane tablets) after taking tamoxifen for 2-3 years experienced a significant reduction in the risk of disease-free survival (DFS) events compared to women who continued on tamoxifen for a full five years of treatment. This study was a randomized, double-blind, multinational trial of postmenopausal women with early breast cancer evaluating the clinical benefits of switching 2,352 patients to Aromasin after 2-3 years of tamoxifen versus continuing 2,372 patients on tamoxifen for a full 5 years of therapy. The primary endpoint of the study was DFS in the intent-to-treat (ITT) population. In postmenopausal women with early breast cancer at a median follow-up of 91 months, switching to AROMASIN after two to three years of tamoxifen, for a total of five years of treatment, was shown to result in a 16% reduction in the risk of DFS events, defined as local or distant recurrence of breast cancer, contralateral breast cancer, or death from any cause, compared to staying on tamoxifen for five years (HR=0.84; 95% CI: 0.75-0.94; P=0.002) in the ITT population. For the secondary endpoint of overall survival in the ITT population, there was an 11% relative risk reduction of death. There was a statistically significant 14% reduction in the risk of death noted in the ER+/unknown population (HR=0.86: 95% CI: 0.75-0.99 P=0.04).

Aromasin is indicated for the adjuvant treatment of postmenopausal women with estrogen-receptor positive early breast cancer who have received 2-3 years of tamoxifen and are switched to Aromasin for completion of a total of five consecutive years of adjuvant hormonal therapy. Aromasin is also indicated for the treatment of advanced breast cancer in postmenopausal women whose disease has progressed following tamoxifen therapy.

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