Arimidex Beats Tamoxifen in Keeping Breast Cancer at Bay

By Amanda Gardner
HealthDay Reporter
Saturday, December 15, 2007; 12:00 AM

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FRIDAY, Dec. 14 (HealthDay News) -- The aromatase inhibitor drug Arimidex continues to outpace the old standard tamoxifen when it comes to preventing recurrences of hormone-receptor-positive breast cancers in postmenopausal women.

Even three years after treatment was stopped, women taking Arimidex still saw a benefit, researchers said.

"It has been very good news," said Dr. Aman Buzdar, U.S. principal investigator of the ATAC (Arimidex or Tamoxifen Alone or in Combination) trial, the results of which were expected to be presented Friday at the 2007 San Antonio Breast Cancer Symposium.

"A lot more women receiving Arimidex are free of cancer compared to tamoxifen, and the 100-month data show that these differences, if anything, with time actually continued to increase -- meaning there were fewer and fewer recurrences on Arimidex compared with tamoxifen," Buzdar said.

"Arimidex is the standard of care for postmenopausal women with receptor-positive breast cancer," confirmed Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La. "One hundred months [over eight years] of follow-up is very profound. It's a true credit to the investigators to be able to do the study and have that much follow-up, and it shows that we have reached a new level of care for postmenopausal women. That's what I use and continue to use."

Hormone-receptor-positive cancers respond to circulating estrogen or progesterone. Experts estimate that from 50 percent to 70 percent of breast cancers are hormone receptor positive.

The new findings were also expected to be published in the journal The Lancet Oncology to coincide with the presentation.

Arimidex (anastrozole) is an aromatase inhibitor, a relatively new class of compounds that blocks estrogen production in the body. According to Buzdar, who is professor of medicine and deputy chair of the department of breast medical oncology at the University of Texas M.D. Anderson Cancer Center, Arimidex is now indicated for postmenopausal women who have a hormone-dependent cancer.