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. The small study reviewed here suggests that Zometa also may lower the risk of breast cancer spreading to the bones.
While promising, these results are early results. More research is needed to figure out if Zometa can reduce the risk of breast cancer spreading to the bone over time.
The 120 women in this study were diagnosed with stage II or stage III breast cancer that had spread to the lymph nodes or other areas near the breast. When the women were diagnosed, CAT scans and PET scans didn't show any evidence that the breast cancer had spread to the bone. Still, the doctors also did bone marrow biopsies on the women. Even though the routine tests didn't show any signs of cancer in their bones, the bone marrow biopsies showed that 40% of the women had breast cancer cells in their bones.
About half of the women in the study got Zometa intravenously every 3 weeks after being diagnosed.
Three months after the women started getting Zometa, the doctors did another bone marrow biopsy on all the women in the study. Whether they got Zometa or not, the percentage of women who had cancer cells in their bone marrow dropped. But the drop was much larger in the women who got Zometa:
These results suggest that Zometa may make it harder for breast cancer cells to survive, grow, and reproduce in bone. This could mean that the risk of breast cancer spreading to the bone might be lower if Zometa is given when breast cancer is diagnosed.
The researchers plan to treat the women in the Zometa group for a full year with the medicine and monitor all the women in this study for any future spread of breast cancer to the bone.
Zometa belongs to a group of medicines called bisphosphonates. 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). Some of these bisphosphonates, such as Fosamax and Actonel, are taken by mouth and are used to treat osteoporosis. Zometa, Aredia, and Bonefos are given intravenously and are generally used when cancer has spread to the bone. Like the study reviewed here, other research suggests that Bonefos also might slow the spread of breast cancer to the bones.
Because these results are early, the researchers aren't sure that a lower risk of finding breast cancer cells in the bone marrow biopsies of women who got Zometa actually translates into in a lower risk of breast cancer spreading to the bones. It's too soon to say whether regularly getting Zometa (or another bisphosphonate) after breast cancer diagnosis will reduce the risk of breast cancer spreading to bone in the future.
Still, bisphosphonate medicines can be an important part of a breast cancer treatment plan. If you're being treated for early-stage breast cancer, your doctor may recommend a bisphosphonate medicine to strengthen your bones since some treatments can weaken bones. If you're being treated for advanced-stage breast cancer that has spread to the bone, your doctor may recommend a bisphosphonate medicine to strengthen your bones, help ease bone pain, or to help keep your calcium levels normal.
Stay tuned to Breastcancer.org for the latest news on research that may lead to better ways to prevent, diagnose, and treat breast cancer.
WASHINGTON (Reuters) - A drug prescribed to prevent fractures in breast cancer patients whose tumors have spread may actually help slow the cancer itself, U.S. researchers reported on Thursday.
They said Zometa, sold by Swiss drug giant Novartis, appears to have prevented the spread of tumors to the bone.
The study, released in preliminary form ahead of a meeting of the American Society of Clinical Oncology, suggests the drug may be useful for more breast cancer patients.
"Tumor cells are continually being released from the primary tumor," Dr. Rebecca Aft, of Barnes Jewish Hospital and Washington University in St. Louis, said in a statement.
"It is thought that the bone marrow harbors these cells and that these cells are likely to evolve into metastatic disease. We think that zoledronic acid changes the bone marrow so that cancer cells are unable to lodge there."
Full details of the study will be released June 3 at the ASCO meeting in Chicago.
Zometa, known generically as zoledronic acid, is in a class of drugs known as bisphosphonates. They are usually prescribed to treat or prevent osteoporosis, but Zometa is mainly used to strengthen the bones of cancer patients whose tumors have spread to the bone.
Breast and other cancers commonly spread to the bone and patients can be crippled by the pain and fractures that result.
Aft's team studied 120 women with stage 2 or stage 3 breast cancer, which has spread into lymph nodes or other areas near the breast. Some got intravenous infusions of Zometa every three weeks for a year, while others did not.
At the time of diagnosis, none of the patients had evidence of any spread when checked using computed tomography (CT) or positron emission tomography (PET) scans. But bone marrow samples showed about 40 percent of the patients had detectable breast tumor cells in their bone marrow.
After treatment, the researchers took more bone marrow samples.
They said 23 percent of women who got Zometa had tumor cells in the bone marrow after three months, compared to 36 percent of those who did not get the drug.
"If longer follow-up shows that women without tumor cells in their bones do not go on to develop metastatic disease, then it would be reasonable to say that bisphosphonates will likely benefit women with locally advanced breast cancer," Aft said.
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