No disease-free survival effect with zoledronic acid for breast cancer
MedWire News: Zoledronic acid (ZA) does not improve disease-free survival (DFS) among women with stage II/III breast cancer, according to results of the Adjuvant Treatment with Zoledronic Acid in Stage II/III Breast Cancer (AZURE) trial.
The study results were presented by Robert Coleman (University of Sheffield, UK) at the 33rd Annual Cancer Therapy and Research Center-American Association for Cancer Research San Antonio Breast Cancer Symposium in Texas, USA, this week.
Coleman explained that the AZURE trial was initiated following research suggesting that agents targeting bone, such as zolendronic acid, may be useful in preventing breast cancer metastasis.
The trial included 3360 patients with stage II/III breast cancer from 174 centers. Coleman and colleagues randomly assigned the patients to receive standard therapy or standard therapy plus ZA, for 5 years.
During a median follow-up period of nearly 5 years, there was no significant difference in DFS between patients who received ZA and those who did not (hazard ratio = 0.98).
However, subgroup analysis showed that there was a significant treatment effect according to menopausal status. Among 1101 patients who were at least 5 years post-menopause, there was a 29% improvement in overall survival among those in the ZA group, compared with those who did not receive ZA.
In contrast, there was no difference between the groups among premenopausal women.
"To see a survival advantage like this is quite remarkable, and the difference in outcome between this group and the younger population is unlikely to be a chance finding. We will clearly want to investigate further in this population," he said.
Coleman added that the findings will "likely dissuade clinicians from giving adjuvant bisphosphonates [such as ZA] on a routine basis to younger women taking adjuvant chemotherapy because, although the drug is generally well tolerated, there is a small risk of osteonecrosis of the jaw."
Indeed, the researchers identified 17 (1.1%) confirmed cases of osteonecrosis of the jaw over the duration of the study period.
Coleman noted that the AZURE findings differ from those of the ABCSG (Austrian Breast and Colorectal Cancer Study Group)-12 study, which evaluated ZA in premenopausal women with hormone-sensitive, early-stage breast cancer, and found improved DFS among women taking ZA.
The differences observed may be due, in part, to methological differences, but this theory needs further investigation, he said.
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By Laura Dean