Anastrozole More Effective Than Tamoxifen In Early Disease.(breast cancer)

2002 JAN 10 - (NewsRx.com & NewsRx.net) -- New data presented at the December 2001 San Antonio Breast Cancer Meeting demonstrate for the first time that an aromatase inhibitor Arimidex (anastrozole) is significantly more effective and has a number of important tolerability benefits over the current treatment standard, Tamoxifen, as an adjuvant treatment in postmenopausal women with early breast cancer.

Arimidex significantly prolonged disease-free survival (DFS), i.e., it reduced the risk of local, contralateral and distant breast cancer recurrence compared with Tamoxifen treatment. This is the first time ever that the established benefits of Tamoxifen in early breast cancer have been surpassed by another treatment, and it marks an incredibly important breakthrough in the management of this increasingly prevalent disease. Arimidex is already licensed for use in advanced breast cancer in postmenopausal women and regulatory approval for this new indication is currently being sought.

These new data are the initial results from the ATAC (Arimidex, Tamoxifen Alone or in Combination) study - the largest adjuvant breast cancer trial ever conducted. Principal investigator, Professor Michael Baum, from University College Hospital, London, U.K., who presented the results, described the outcome as extremely important for women with early breast cancer.

"These are very exciting new data that suggest that we might have something better than Tamoxifen in efficacy and tolerability, bearing in mind that Tamoxifen has been the gold standard for 20 years," Baum stated. "I am also excited by the potential for Arimidex for the prevention of breast cancer."

After a median of 33 months follow-up and a median duration of treatment of 30.7 months, Arimidex monotherapy was found to be significantly more effective in prolonging disease-free survival (DFS) than Tamoxifen. Only 317 of 3125 women in the Arimidex group had a relapse of their breast cancer or died compared with 379 of 3116 women in the Tamoxifen group (p=0.0129; HR=0.83, CI=0.71-0.96). This represents a 17% reduction in the risk of breast cancer recurring with Arimidex treatment compared with Tamoxifen. Among women with confirmed hormone-sensitive tumors, the reduction in risk with Arimidex compared with Tamoxifen was even more striking, at 22% (p=0.0054; HR=0.78, CI=0.65-0.93).

The Arimidex/Tamoxifen combination showed no additional efficacy or tolerability benefits compared with Tamoxifen alone. There were no safety issues associated with the combination treatment.

Arimidex was also found to have many important tolerability advantages over Tamoxifen. Most strikingly, Arimidex was associated with significantly fewer reports of endometrial cancer when compared with Tamoxifen. This finding was supported by a significantly lower incidence of vaginal bleeding and vaginal discharge among Arimidex-treated patients compared with those taking Tamoxifen. Another known risk associated with Tamoxifen is thromboembolic events. In the ATAC trial, both the overall incidence of thromboembolic events and that of deep vein thromboses were significantly reduced in the Arimidex group.