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Zoledronic Acid Prevents Cancer Treatment-Induced Bone Loss in Breast Cancer Patients Treated with Hormone Therapy
San Antonio, Texas (ots) -
- First Data from Large Trial in Premenopausal Women Show Strong
Zoledronic acid prevents loss of bone mass caused by adjuvant treatment with an aromatase inhibitor or tamoxifen and the luteinising hormone-releasing hormone analog (LHRHa) goserelin in premenopausal women with early-stage hormone receptor-positive breast cancers. This new clinical finding was presented today at the annual San Antonio Breast Cancer Symposium.
For the first time, a large multicenter clinical trial has shown how to prevent cancer treatment-induced bone loss (CTIBL) and established that such bone loss is a frequent side effect of hormonal therapy for breast cancer in premenopausal women. The study is sponsored by the Austrian Breast and Colorectal Cancer Study Group, which is headquartered in Vienna. The analysis was presented by lead investigator Michael Gnant, M.D., Professor of Surgery at the University of Vienna.
"Although bone mass loss has been a well-known medical issue for postmenopausal women receiving adjuvant hormone therapy, the extent of the problem for premenopausal patients is not known." Dr. Gnant said. "The oncology community has been waiting for data to show if treatment with zoledronic acid could prevent this side effect."
Based on their results, the investigators suggest that women with breast cancer who receive adjuvant treatment with aromatase inhibitors or tamoxifen in conjunction with the LHRHa goserelin also receive regular measurements of bone mineral density (BMD). They also recommend that treatment with zoledronic acid be considered to prevent cancer treatment-induced bone loss.
The majority of breast cancers are hormone receptor-positive, meaning that the hormone estrogen makes the tumors grow. Whereas tamoxifen blocks the effects of estrogen on tumor growth, aromatase inhibitors - a newer class of hormonal treatments - and goserelin reduce the amount of estrogen in a woman's body.
ABCSG-12 is a large, multicenter, randomized Phase III clinical trial comparing the aromatase inhibitor anastrazole with tamoxifen in the adjuvant treatment of hormone-responsive breast cancer in premenopausal patients in combination with the LHRHa goserelin. As of October 2004, a total of 1315 patients had been randomized into one of four treatment arms. Clinical endpoints of the study are relapse-free survival (RFS), overall survival (OS) and BMD.
Following surgery (and radiation therapy, if necessary) patients with stage I and II breast cancer received goserelin and then were randomized into the four treatment arms:
2. Tamoxifen + Zoledronic Acid
4. Anastrazole + Zoledronic Acid
The adjuvant therapy consisted of goserelin (3.6 mg s.c. every 28 days) plus oral tamoxifen (20 mg/day) or oral anastrozole (1 mg/day), for three years. In this trial, for each hormonal therapy arm, patients received zoledronic acid or placebo. Zoledronic acid was given as a 4mg, 15-minute intravenous infusion every six months.
In the final analysis, 401 patients received BMD measurements at baseline, 6 months, 1 year and 3 years. Patients who received combination hormone therapy without zoledronic acid had significant bone loss after 1 and 2 years (overall: minus 12% after 2 years). Bone loss was significantly more severe in patients receiving combination therapy with goserelin and the aromatase inhibitor anastrozole (mean -16%) than in patients receiving goserelin with tamoxifen (mean -8%). Patients who received zoledronic acid with the combination therapy had stable BMD with no treatment induced bone loss (p<0.0001). These results appeared to be independent of age and other risk factors.
About the Austrian Breast and Colorectal Cancer Study Group
The Austrian Breast and Colorectal Cancer Study Group (ABCSG) is a cooperative institution that was set up to conduct controlled clinical trials in breast and colorectal cancer and to facilitate communication and the dissemination of knowledge among scientists and others dedicated to the cancer problem. Since the establishment of ABSCG in 1984, a total of 13,000 patients have been enrolled in the group's investigations. In certain patient risk groups, ABCSG is currently recruiting up to 40% of all Austrian breast cancer patients in clinical trials. The goal of ABCSG is to enhance the standard of cancer treatment in Austria and abroad by developing innovative approaches and testing increasingly effective therapeutic strategies.
Contact: Susan Heins Tel. +1/864/286'95'97