Zometa (chemical name: zoledronic acid) is a medicine used to strengthen bones in women diagnosed with breast cancer that has spread to the bone. Zometa can reduce bone pain and the risk of fractures. A study suggests that Zometa also may lower the risk of early-stage breast cancer coming back.
More than 1,800 premenopausal women being treated for hormone-receptor-positive, early-stage breast cancer got either tamoxifen or Arimidex (chemical name: anastrozole) after surgery and treatment (either medicine or more surgery) to shut down the ovaries. Both tamoxifen and Arimidex are hormonal therapy medicines. About half of the women also got Zometa along with the hormonal therapy medicine. Zometa was given intravenously every 6 months, for a total of 3 years.
Women who got Zometa with the hormonal therapy medicine were 36% less likely to have the breast cancer come back 5 years after treatment than women who got only hormonal therapy medicine:
- 6% of the women who got Zometa died or had the breast cancer come back 5 years later
- 9% of the women who didn't get Zometa died or had the breast cancer come back 5 years later
More than 90% of the women in this study didn't have the breast cancer come back 5 years after treatment, whether or not Zometa was part of the treatment plan.
Estrogen can tell hormone-receptor-positive breast cancers to grow. So many premenopausal women diagnosed with hormone-receptor-positive breast cancer either will have their ovaries removed or take medicine after surgery to shut down their ovaries to lower estrogen levels and reduce the risk of the breast cancer coming back. To limit the effects of any remaining estrogen, these women also often take hormonal therapy medicine.
Tamoxifen, which blocks the effect of estrogen on breast cancer cells, often is given to premenopausal women. In this study some of the women were treated with tamoxifen while other women got the aromatase inhibitor Arimidex. Aromatase inhibitors, which block the production of estrogen, usually are given only to postmenopausal women. This study's use of Arimidex in premenopausal women was unusual.
Premenopausal women who take medicines that shut down their ovaries and hormonal therapy medicines after surgery essentially go through menopause because of treatment. This treatment approach dramatically lowers the risk of the breast cancer coming back, but bone loss or weakening (osteoporosis) can be a side effect. So also giving these women a bone-strengthening medicine makes sense. This research suggests that if the bone-strengthening medicine is Zometa, the risk of the cancer coming back also could be lower.
Zometa belongs to a group of medicines called bisphosphonates. All of the bisphosphonates help build bone strength. Other bisphosphonates are Fosamax (chemical name: alendronate), Actonel (chemical name: risedronate), Aredia (chemical name: pamidronate), and Bonefos (chemical name: clodronate).
Fosamax and Actonel are taken by mouth and are used to treat osteoporosis. Zometa and Aredia (given intravenously), and Bonefos (taken by mouth), generally have been used only to strengthen bones in women diagnosed with advanced breast cancer that has already spread to the bone. Research has shown that treatment with Zometa and Bonefos might actually slow the spread of breast cancer to the bones.
This is the first research study to show that Zometa, when combined with ovarian shutdown and hormonal therapy, might help lower the risk of breast cancer coming back in premenopausal women diagnosed with early-stage, hormone-receptor-positive breast cancer. Other research is looking at whether Zometa might lower the risk of breast cancer coming back in postmenopausal women diagnosed with early-stage breast cancer.
In rare cases, taking Zometa or another bisphosphonate can cause a very serious side effect called osteonecrosis of the jaw. This happens when some healthy bone cells die off in a way that's not normal. Osteonecrosis of the jaw usually is seen only in people who have had teeth removed or other dental procedures while taking a bisphosphonate. In this study, none of the women who took Zometa developed osteonecrosis of the jaw or any other serious side effects.
It's not clear how Zometa works to help lower the risk of breast cancer coming back. It's also not clear if Zometa will help lower the risk of cancer coming back in premenopausal women getting chemotherapy. This study was done in Europe; chemotherapy isn't used as often in premenopausal women in Europe as it is in the United States. None of the women in this study got chemotherapy. In the United States, many women similar to those in this study would receive chemotherapy. More research is needed to better understand how Zometa should be used as part of a treatment plan for early-stage breast cancer.
If you're being treated for breast cancer, you might want to ask your doctor about your bone health and bone-strengthening medicines. A bone-strengthening medicine may make sense for you during and after breast cancer treatment.
Stay tuned to Breastcancer.org for the latest news on research that may lead to better ways to prevent, diagnose, and treat breast cancer.