Taking Zoledronic Acid Less Often After the First Year of Treatment Is Safe for Women with Metastatic Breast Cancer

ASCO Annual Meeting
May 30, 2014

According to new findings from a phase III clinical trial, women taking zoledronic acid (Zometa) for breast cancer that has spread to the bone, called metastases, can safely scale back to a once-every-three-months schedule after finishing a year of monthly treatments.

Zoledronic acid is often used to reduce complications from bone metastases, such as broken bones and spinal cord compression. Most doctors give zoledronic acid once every four weeks starting as soon as bone metastases are diagnosed. It is thought that treatment should continue indefinitely, but some doctors have concerns that continuing the monthly schedule for the long term may increase the risk of serious side effects like kidney problems and osteonecrosis of the jaw (ONJ). ONJ can cause pain, swelling, and infection of the jaw; loose teeth; and exposed bone. Currently, there are no recommendations for how often zoledronic acid should be given after the first year of treatment.

To find out if increasing the time between zoledronic acid treatments after a year of monthly therapy would be safe and effective, 403 women with bone metastases from breast cancer were divided into two groups. One group continued to receive zoledronic acid every month, and the other group received zoledronic acid every three months for an additional year.

The researchers found that the percentage of women who developed fractures, spinal cord compressions, or needed radiation therapy or surgery because of bone metastases were similar in both groups (22% in the monthly group compared with 23% percent in the every-three-months group). There were no differences in pain levels or the use of pain medications between the two groups. The researchers also observed no obvious differences in kidney side effects or the overall safety profile of the treatment between the two groups. However, two women in the monthly group developed osteonecrosis of the jaw compared with none in the every-three-months group.

What this means for patients

“The addition of bone-modifying drugs like zoledronic acid has dramatically improved the care of patients with bone metastases. But long-term treatment carries the risk of serious side effects, such as osteonecrosis of the jaw and kidney problems,” said lead study author Gabriel N. Hortobagyi, MD, a professor of medicine at the MD Anderson Cancer Center in Houston, TX. “We found that less frequent treatment may reduce the risk of these serious side effects, with added benefits in reduced patient inconvenience and cost.”

Questions to ask your doctor

  • Do you recommend treatment with a bone-modifying drug?
  • How long will I need to take this drug, and how often will it be given?
  • What side effects can I expect from this treatment?
  • What is the risk of developing osteonecrosis of the jaw?
  • What signs or symptoms should I watch for?
  • How will my treatment be monitored?

More Information

Guide to Breast Cancer

ASCO Answers Fact Sheet: When Cancer Spreads to the Bone (PDF)

Bone-Modifying Drugs for Breast Cancer

Dental and Oral Health