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CHICAGO -- One bone-preserving drug is as good as another in early stage breast cancer, a researcher said here.

In a large randomized trial, there were few differences in anti-cancer efficacy among three different members of the bisphosphonate class, according to , of the University of Washington in Seattle.

And the overall safety of the drugs was also similar, Gralow reported at the

But the study might not help settle a continuing controversy in oncology over the use of the drugs, which normally are prescribed to slow bone embrittlement by inhibiting the action of osteoclasts.

The "impetus for the study" was the assumption that bisphosphonates have a direct cancer-fighting effect -- something that has been controversial, commented , of Dana-Farber Cancer Institute in Boston, so it makes sense that it might prevent fractures in cancer patients.

Because the study had no placebo arm, he told 番茄社区app, "we still can't say if bisphosphonates are important" in cancer treatment, although they remain important to treat bone issues.

But if there is a cancer-fighting effect, "they're all the same," he said.

Gralow and colleagues enrolled 6,097 women with stage 1 through 3 breast cancers who were getting adjuvant systemic therapy after surgical treatment of their tumors.

They were randomly assigned to get 3 years of zoledronic acid, clodronate, or ibandronate. Zoledronic acid is given by injection while the other drugs are given orally.

The primary endpoint of the study was disease-free survival, and secondary endpoints included overall survival and adverse events, Gralow reported.

After a fourth interim analysis in September 2014, she said, the data safety monitoring committee concluded that the pattern of events was unlikely to change and recommended releasing the results.

Data as of April showed 512 deaths after a median follow-up of 5.4 years, Gralow reported. Analysis showed:

• The 5-year disease-free survival rate was 88% and did not differ by treatment arm.
• Results varied slightly by tumor type, but within types, the drug treatment made no difference.
• The 5-year overall survival rate was 93%, with again no difference by drug type.
• The rate of grade 3 and 4 adverse events was not significantly different among the arms.
• On the other hand, patients getting zoledronic acid had an elevated risk of osteonecrosis of the jaw at 1.27%, compared with 0.31% for clodronate and 0.71% for ibandronate, a significant difference at P=0.003.
• Fracture rates did not differ by arm.

One of the take-home messages from the study is that "people did really, really well," commented , of Yale School of Medicine.

"The study population was very representative of real life" in the clinic, she told 番茄社区app, so the results should be broadly applicable.

"I think a lot of us have been looking for excuses to use these types of drugs," she told 番茄社区app, but many have been reluctant to do so unless indicated by bone issues.

"We've been waiting for some good data" about the value of the drugs in cancer outcomes, she said.

Additional evidence that bisphosphonates do have an anti-cancer effect is forthcoming shortly, according to , of the University of Sheffield in England.

In a formal discussion of Gralow's paper, he noted that a meta-analysis by the , now in press, found that treatment with bisphosphonates was associated with a 33% reduction in bone metastases and an 18% reduction in the risk of death.

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