News Release

Study confirms long-lasting anticancer benefit of zoledronic acid for women with early-stage breast cancer

Peer-Reviewed Publication

The Lancet_DELETED

Women with early-stage hormone receptor-sensitive breast cancer* given zoledronic acid, a bone strengthening drug, in addition to standard hormone therapy for 3 years following surgery are at significantly (32%) less risk of their cancer returning, and the effect is long lasting, according to the long-term results of the landmark Austrian Breast and Colorectal Cancer Study Group trial-12 (ABCSG-12) published Online First in The Lancet Oncology.

Bone marrow provides a fertile sanctuary for disseminated tumour cells released from primary breast cancer tumours from where they can spread to other organs. Previous research suggests that bisphosphonates such as zoledronic acid (which reduces bone loss by slowing down the activity of cells that destroy bone) might have the ability to modify the bone microenvironment making it less favourable for cancer-cell survival thereby reducing the spread of tumour cells to other parts of the body.

The ABCSG-12 trial was designed to establish whether bisphosphonate treatment (zoledronic acid) could increase disease-free survival (DFS) in premenopausal women with early hormone receptor-sensitive breast cancer when given in addition to standard hormonal therapy following surgery. Between 1999 and 2006, over 1800 women were enrolled and randomly assigned to either tamoxifen, tamoxifen plus zoledronic acid (an infusion every 6 months), anastrozole, or anastrozole plus zoledronic acid (an infusion every 6 months).

In 2009, initial results (median 48 months follow-up) reported that zoledronic acid significantly reduced the risk of disease recurrence by 36% and also showed a trend towards improved overall survival.

In this study, Michael Gnant from the Medical University of Vienna, Vienna, Austria and colleagues report the median 62 month follow-up of women from the ABCSG-12 trial.

More than 2 years after stopping treatment, zoledronic acid was associated with significantly better DFS compared with hormone therapy alone (92% vs 88%), reducing the likelihood of the cancer coming back by 32%. DFS was similarly improved regardless of whether the women were taking tamoxifen or anastrozole, although overall survival was worse in patients receiving anastrozole.

Zoledronic acid was associated with continued reduction in distant recurrences in bone and non-bone sites, local recurrence, and breast cancer in the opposite breast.

Zoledronic acid was generally well tolerated and adverse events were generally mild (arthralgia [joint pain], bone pain, and pyrexia [fever]) with no cases of renal failure or osteonecrosis of the jaw, and no increase in serious adverse events compared with hormonal therapy alone.

Interestingly, say the authors: "The DFS benefit with zoledronic acid seems to be driven by the subgroup of patients who are older than 40 years of age…[in whom the risk of cancer returning was reduced by 42%]."

They conclude: "Currently, more than 96% of the women enrolled in ABCSG-12 are alive, emphasising that the treatment regimens and duration used are appropriate for this patient population. On the basis of the results of this study, combination of zoledronic acid with adjuvant endocrine therapy (ovarian suppression plus tamoxifen) should be considered for premenopausal women with low-or-moderate risk, early stage, hormone-receptor-positive breast cancer."

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Professor Michael Gnant, Medical University of Vienna, Vienna, Austria. T) +43 1 40400 5646 E) Michael.gnant@meduniwien.ac.at

Or Ms Gitti Grobbauer, ABCSG's commuication manager T) +43 664 5440807 (mobile)


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