When simultaneously administered, zoledronic acid partnered with adjuvant endocrine therapy prevents bone loss in women with breast cancer, and improved bone-mineral density after treatment, according to an article released on August 20, 2008 in The Lancet Oncology. 

For patients with early breast cancer, endocrine therapy is used routinely while the tumors may still respond. One serious side effect in premenopausal women on this treatment is bone loss, which has received serious attention from clinicians. To quantify how endocrine therapy affects bone-mineral density in the presence of concomitant zoledronic acid, Professor Michael Gnant of the Medical University of Vienna, General Hospital of Vienna, and colleagues performed a prospective study of patients included in the Austrian Breast and Colorectal Cancer Study Group trial-12 (ABCSG-12.)

In this trial, premenopausal women were randomized to receive one of two endocrine therapies, either 3 years of goserelin plus tamoxifen or goserelin plus anastrozole. Each of these groups were randomized to receive concomitant zoledronic acid or without, making a total of four subgroups. A total 404 women were included in this substudy, of whom 199 were assigned to endocrine therapy only, and 205 were assigned the endocrine therapy with zoledronic acid. The women were evaluated for lumbar-spine and trochanter bone-mineral density using dual-energy X-ray absorptiometry. Measurements were taken at 0, 6, 12, 36, and 60 months, and the primary evaluated point was the bone mineral density after one year.

Patients who were only administered endocrine therapy had significant bone-mineral density loss in comparison with their baseline evaluations after 3 years. After 5 years, when the therapy regimen had been completed for 2 years, some bone-mineral density recovery was noted, but not back to baseline levels. The patients on the concomitant therapies, in contrast, remained stable with baseline values at 3 years, and had increased density after 5 years.

In conclusion, the authors note that using zoledronic acid in combination with routine endocrine therapy in premenopausal, early-stage breast cancer patients can potentially maintain their bone-mineral density through this therapy and possibly improve bone mineral density later. “The findings presented here offer important information related to bone health for premenopausal women undergoing adjuvant endocrine therapy,” Notes Prof. Gnant.

Adjuvant endocrine therapy plus zoledronic acid in premenopausal women with early-stage breast cancer: 5-year follow-up of the ABCSG-12 bone-mineral density substudy
Michael Gnant, Brigitte Mlineritsch, Gero Luschin-Ebengreuth, Franz Kainberger, Helmut Kässmann, Jutta Claudia Piswanger-Solkner, Michael Seifert, Ferdinand Ploner, Christian Menzel, Peter Dubsky, Florian Fitzal, Vesna Bjelic-Radisic, Günther Steger, Richard Greil, Christian Marth, Ernst Kubista, Hellmut Samonigg, Peter Wohlmuth, Martina Mittlbock, Raimund Jakesz, on behalf of the Austrian Breast and Colorectal Cancer Study Group (ABCSG)
Lancet Oncol 2008; 9: 840-49
DOI:10.1016/S1470-2045(08)70204-3
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Written by Anna Sophia McKenney