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Title: Long-Term Use of Anastrozole Shows Benefits in Women Who Have Completed Tamoxifen Therapy: Presented at ASCO

"Long-Term Use of Anastrozole Shows Benefits in Women Who Have Completed Tamoxifen Therapy: Presented at ASCO"

By Cameron E. Johnston ORLANDO, FL -- May 23, 2005 -- Women with early-stage breast cancer who complete a 3-year course of anastrozole (Arimidex) therapy after their tamoxifen regimen appear to have a reduced rate of disease relapse than women who stop all therapy after tamoxifen. The results, from the Austrian Breast Cancer Study Group-6a, were presented here on May 15[^th at the American Society of Clinical Oncology Annual Meeting (ASCO) by Raimund Jakesz, MD, head of the study group and professor of medicine, University Surgery Clinic, Vienna Medical School, Vienna, Austria.

The study involved only women who were enrolled in the original Austrian Breast Cancer Study Group 6 and whose breast cancer had not progressed after 5 years of adjuvant tamoxifen.

The new study randomized 387 women to anastrozole 1 mg/day and 469 to no further treatment for a total of 3 years.

During a median period of 5 years, the women underwent rigorous safety monitoring that included chest x-rays, mammography, pelvic ultrasound, and gynecologic examinations at 12-month intervals, and serum enzymes, electrolytes and blood counts every 3 months.

The primary endpoint of the study was recurrence-free survival, local or distant metastasis, or new tumors in the contralateral breast.

The women in both groups were matched for age and disease characteristics at baseline.

Results show a 36% reduction in the incidence of loco-regional and distant recurrences or new cancers in the contralateral breast in favor of anastrozole (95% CI, 0.41 - 0.99, P = .047)

Loco-regional recurrences were seen in 10 women in the anastrozole group compared with 15 women in the control group. Distant metastases were seen in 16 women and 35 women, respectively. Cancers in the contra-lateral breast were seen in 6 women in the study group and 10 in the control group. Other secondary tumors were recorded in 18 and 23 women, respectively.

Dr. Jakesz said the findings lend support the use of anastrozole as continued maintenance therapy in women who have been treated successfully for early-stage breast cancer.

He pointed out that a well-known randomized study that evaluated the use of another aromatase inhibitor -- letrozole -- in postmenopausal women who had completed 5 years of tamoxifen therapy was halted early, after 2.4 years, when interim results showed letrozole was superior to placebo. However, Dr. Jakesz said, safety concerns about the long-term use of letrozole remain to be answered.

[Presentation title: Extended Adjuvant Treatment With Anastrozole: Results From the Austrian Breast and Colorectal Cancer Study Group Trial 6a (ABCSG-6a). Abstract 527]

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