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Better Survival Seen for Early Breast Cancer Patients Switched From Tamoxifen to Exemestane
"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 common cancers occurring in women with more than one million women diagnosed each year worldwide. "The Aromasin overall survival data announced today means that women are moving closer to the goal of longer survival." said Lead US Investigator, Stephen Jones, M.D., medical director, and co-chair, breast cancer research committee of the US Oncology Research Network and director of breast cancer research at the Texas Oncology Baylor-Sammons Cancer Center in Dallas.
With the new 5 year follow-up data, no clinically meaningful changes in the safety profile were noted. According to Professor Coombes, "We have also now been able to study the long-term effects of exemestane after completion of therapy, and our results provide women and their physicians with important long-term information on the use of exemestane."
At 34.5 months of follow-up, the most common side effects were mild-to-moderate and include hot flushes (21.2% for Aromasin vs. 19.9% for tamoxifen), fatigue (16.1% vs. 14.7%), arthralgia (14.6% vs. 8.6%), headache (13.1% vs. 10.8%), insomnia (12.4% vs. 8.9%), and increased sweating (11.8% vs. 10.4%). AROMASIN should not be used in women who are premenopausal, are nursing or pregnant, have a known hypersensitivity to the drug, or are taking estrogen-containing agents. Dose modification is recommended for patients who are receiving certain medications, including strong CYP 3A4 inducers. In patients with early breast cancer, elevations in bilirubin, alkaline phosphatase, and creatinine were more common in those receiving AROMASIN than either tamoxifen or placebo.
Aromasin was approved in the United States in 2005 for treatment of postmenopausal women with estrogen-receptor positive early breast cancer following two-to-three years of tamoxifen, for a combined total of five consecutive years of therapy. It also is approved for use in Canada, Europe, Japan and South America. Currently, Aromasin is available in more than 80 countries and approved in the early breast cancer setting in more than 40 countries.