Pfizer Inc. has received European Mutual Recognition Procedure (MRP) approval to market Aromasin (exemestane tablets) for a new indication, adjuvant treatment of estrogen receptor positive invasive early breast cancer following two-to-three years of initial adjuvant tamoxifen therapy in postmenopausal women.

Aromasin is a hormonal therapy, used to treat women with breast cancers that depend on a hormone, specifically estrogen, for growth and survival. An estimated two-thirds of breast cancer cases are estrogen-dependent.

The approval was based on the Intergroup Exemestane Study (IES) that showed patients who switched to Aromasin after two to three years of tamoxifen had a 31 per cent better probability of disease-free survival than those who remained on tamoxifen.

The trial involved over 4,700 postmenopausal women with estrogen-receptor positive breast cancer who were followed for an average of 35 months. Patients receiving Aromasin experienced a significant reduction in the risk for recurrence of the disease, as compared to those continuing on tamoxifen. This reduction includes fewer local and distant tumours as well as new cancer in the other breast.

In the IES study, treatment with Aromasin was associated with fewer of the potentially serious side effects commonly associated with tamoxifen, including a significant reduction in thromboembolic events. Additionally, Aromasin had no significant impact on bone fracture rate.