Osteoporosis drug may extend survival in older, not younger, breast cancer patients

Though initially approved by the U.S. Food and Drug Administration (FDA) for use among osteoporosis patients, zoledronic acid may double as a life-extending therapy for older women with breast cancer.

However, younger women with breast carcinomas mighty actually experience harmful side effects from the drug, placing its net value as a supplementary breast cancer therapy at zero.

Such was the conclusion of an investigation conducted among the more than 3,600 participants in the Adjuvant Zoledronic Acid to Reduce Recurrence (AZURE) clinical trial. Published in a recent issue of the New England Journal of Medicine, the study set out to determine whether or not the medicine might prevent breast cancer from forming secondary bone tumors.

This is not the first instance that a bisphosphonate has been tested for its applications in the field of oncology. For instance, a presentation at the 2011 European Multidisciplinary Cancer Congress announced that the popular osteoporosis drug ibandronate might prevent the fractures associated with prostate tumors that spread to the bones.

In the new study, researchers followed the health and wellness of breast cancer patients enrolled in 174 clinics worldwide, in locales as far-flung as Spain, Portugal, Thailand, Taiwan, Australia and the UK.

All participants were given either chemotherapy or hormone-based treatments as a cancer treatment, and one half were also prescribed zoledronic acid.

Researchers found that, contrary to what smaller studies have suggested, this bisphosphonate did not improve disease-free survival or overall survival time. However, their findings were uniquely bifurcated by age.

Essentially, postmenopausal women experienced improvements in survival time and a decrease in the risk of bone metastases. The team estimated that the five-year, postmenopausal breast cancer survival increased from 79 to 85 percent.

Even more dramatically, elderly participants who took zoledronic acid experience one half as many bone metastases as those who were not given the pharmaceutical.

That said, all other women - whether premenopausal or menopausal - not only did not benefit from zoledronic acid but also risked potential harm. Likewise, their overall survival did not improve after taking the drug.

Researchers concluded that zoledronic acid may have applications as a supplementary therapy for postmenopausal breast cancer patients.

"Our findings could mean a major new treatment approach for the tens of thousands of women...who develop breast cancer," the team concluded, noting that further investigation is warranted.

The National Cancer Institute estimates that in the U.S., 2 million living women have a history of breast cancer. By contrast, about 8 million women are living with osteoporosis, according to the National Osteoporosis Foundation.