NEW YORK -- August 19, 2008 -- Concomitant zoledronic acid prevents bone loss in women with breast cancer during treatment with adjuvant endocrine therapy and improves bone mineral density (BMD) after treatment, according to a study published online and in the September edition of The Lancet Oncology.
Michael Gnant, Professor, Medical University of Vienna, General Hospital of Vienna, Vienna, Austria, and colleagues conducted a prospective BMD substudy of patients included in the Austrian Breast and Colorectal Cancer Study Group trial-12 (ABCSG-12) to quantify the long-term effect of endocrine therapy and that of concomitant zoledronic acid on BMD.
Premenopausal women with early-stage breast cancer (N = 404) participated in the substudy and were randomly assigned to receive 3-year treatment of either goserelin plus tamoxifen with or without zoledronic acid or goserelin plus anastrozole with or without zoledronic acid. Of these participants, 199 received endocrine therapy alone and 205 received endocrine therapy with zoledronic acid. Lumbar-spine and trochanter (hip) BMD was measured by dual-energy x-ray absorptiometry at baseline and at 6, 12, 36, and 60 months. The primary endpoint was change in BMD at 12 months.
After 3 years of treatment, patients assigned endocrine therapy alone had significant loss of BMD at the lumbar spine and hip compared with baseline levels. At 5 years (2 years after completion of therapy), partial recovery of BMD was noted, although values were still below baseline. By contrast, in patients randomised to endocrine therapy and concomitant zoledronic acid, BMD remained stable at 3 years at the lumbar spine and hip and increased at 5 years above baseline values.
This substudy shows that the addition of zoledronic acid to routine endocrine therapy in premenopausal women with early-stage breast cancer can sustain BMD during 3 years of endocrine therapy and actually improve it 2 years after completion of therapy.
Prof. Gnant says, "The findings presented here offer important information related to bone health for premenopausal women undergoing adjuvant endocrine therapy."
SOURCE: The Lancet Oncology
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