Zometa (chemical name: zoledronic acid) is used to strengthen bones and lower the risk of breaking a bone and other bone complications in women diagnosed with metastatic breast cancer that has spread to the bones.
Earlier research suggested that Zometa also might help stop breast cancer from spreading to the bones by making it harder for breast cancer cells to grow in bones and might help reduce the risk of the cancer coming back (recurrence) in women diagnosed with early-stage breast cancer.
Results from three studies all suggest that Zometa can help reduce the risk of cancer recurrence when it's included from the start in treating hormone-receptor-positive early-stage breast cancer in postmenopausal and older premenopausal women.
Results from the three studies were presented at the 2011 San Antonio Breast Cancer Symposium.
The Austrian Breast Cancer Study Group (ABCSG) XII trial
More than 1,800 premenopausal women diagnosed with stage I or II hormone-receptor-positive breast cancer participated in this study. After surgery, all the women were treated with Zoladex (chemical name: goserelin) to stop the ovaries from making estrogen (medical ovarian shutdown) and with hormonal therapy. Half the women were randomly assigned to also get Zometa; the other half didn't.
After 7 years of follow-up, breast cancer recurrence was less likely in women who got Zometa compared to women who didn't. Overall, the time the women lived without the cancer coming back (disease-free survival) was 28% better in women who got Zometa. Still, in a finer analysis, the researchers found that only women older than 40 benefited from adding Zometa to the treatment plan. In women older than 40, disease-free survival was 34% better in women who got Zometa. In women younger than 40, disease-free survival wasn't better in women who got Zometa.
The Zometa-Femara Adjuvant Synergy (Zo-FAST) Trial
More than 1,060 women diagnosed with early-stage hormone-receptor-positive breast cancer were in this study. All the women were postmenopausal or weren't having menstrual periods because ovarian function declined due to chemotherapy treatment before surgery. After surgery, all the women got the hormonal therapy Femara (chemical name: letrozole). Half the women also started on Zometa right after surgery (immediate Zometa group). The other half started Zometa if/when they had a decline in bone health (delayed Zometa group). Although the focus of the study was on bone health and using Zometa, the researchers also looked at recurrence risk.
After 5 years of follow-up, recurrence was less likely in women who started Zometa right after surgery compared to women who started Zometa only if they had a decline in bone health. Overall, disease-free survival was 30% better in women in the immediate Zometa group compared to women in the delayed Zometa group.
The Adjuvant Zoledronic Acid to Reduce Recurrence (AZURE) trial
More than 3,355 women diagnosed with stage II or III breast cancer were in this study. The women were both pre- and postmenopausal. After surgery, all the women were treated with hormonal therapy and/or chemotherapy to reduce the risk of recurrence. Half the women were randomly assigned to also get Zometa; the other half didn't get Zometa. Half the women were followed for more than 5 years; the other half were followed for shorter periods of time.
Overall, women who got Zometa were just as likely to have a recurrence as women who didn't get Zometa. Still, when the researchers compared the outcomes of women who were more than 5 years into menopause to the outcomes of premenopausal women and women fewer than 5 years into menopause, they found Zometa did reduce recurrence risk in the women who were menopausal longer. Disease-free survival was 25% better in women 5 or more years into menopause compared to the other women.
Right now, Zometa isn't routinely prescribed to reduce recurrence risk in women diagnosed with early-stage, hormone-receptor-positive breast cancer and it isn't approved for this use. Still, the results of these studies suggest that using Zometa after surgery could help reduce recurrence risk in some postmenopausal women. So it's possible doctors will start using Zometa in this way.
Zometa -- and other bisphosphonates -- may make sense for postmenopausal women to strengthen bones that may be weakened by some breast cancer treatments.
Bisphosphonates used to prevent or treat osteoporosis include:
- Actonel (chemical name: risedronate)
- Boniva (chemical name: ibandronate)
- Fosamax (chemical name: alendronate)
- Reclast (chemical name: zoledronic acid -- the same active ingredient as Zometa)
Reclast is given intravenously once a year. The others are pills taken by mouth.
If you've been diagnosed with early-stage breast cancer, you may want to ask your doctor if a bisphosphonate makes sense for you. If you're a postmenopausal woman, your doctor may recommend a bisphosphonate to strengthen your bones or treat osteoporosis. The studies reviewed here suggest that taking Zometa also could lower your risk of cancer recurrence when started right after surgery. If you're prescribed a bisphosphonate, know that some of them need to be taken in a specific way and all may cause serious side effects; make sure you and your doctor talk about how to take the medicine.