San Antonio (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:
1. Tamoxifen 2. Tamoxifen + Zoledronic Acid 3. Anastrazole
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.
Dana Kahn Cooper