May 31, 2008 (Chicago) -- A potent bone-building drug may cut the risk of relapse in premenopausal women with early breast cancer, a study shows.
In a study of more than 1,800 patients, women who got two injections a year of the bone drug Zometa were about one-third less likely to suffer a recurrence than those who did not.
"Zometa creates a tumor-hostile environment that helps to keep cancer away, and it is very safe," says researcher Michael Gnant, MD, professor of surgery at the Medical University of Vienna, Austria.
Gnant presented the findings at the annual meeting of American Society of Clinical Oncology (ASCO).
Zometa's Antitumor Effects
Zometa is a member of a class of drugs called bisphosphonates, which reduce the risk of fractures in cancers that spread to the bone. Drugs in the bisphosphonate class are also used to treat osteoporosis.
Lab and animal studies suggest that Zometa might also have a range of antitumor effects, Gnant says. The research suggests it can inhibit cell growth, reduce cells' ability to stick to one another, cut off the growth of blood vessels that feed tumors, and stimulate cancer-fighting immune cells.
The new study, conducted by the Austrian Breast & Colorectal Cancer Study Group, involved 1,801 younger women who hadn't gone through menopause and had early breast cancer that was fueled by hormones.
The women were then randomly assigned to standard hormone treatment with either tamoxifen or Arimidex. Tamoxifen is an anti-estrogen that works against estrogen's effect on cells, while Arimidex actually shuts down the body's ability to make estrogen. Both drugs have been shown to help prevent recurrences after surgery for early-stage breast cancer.
Half the women in each group were also given Zometa. The rest got a placebo. They were treated for three years.
Five years later, the risk of relapse was 36% lower in women taking either hormone therapy plus Zometa, compared with hormone therapy alone.
Overall, cancer came back in 6% of women who received Zometa vs. 9% who got the placebo.
There were no differences in the results between women taking tamoxifen and those taking Arimidex.
Zometa was well tolerated, and none of the women developed kidney damage or jaw bone death, two side effects that have been linked to bisphosphonate drugs.
The trial was funded in part by Novartis, which makes Zometa.
Julie Gralow, MD, chairwoman of ASCO's communications committee and a breast cancer specialist at the University of Washington, says that "the findings will change practice."
Based on these data, many breast cancer doctors will start offering the drug to their patients, she tells WebMD.
Eric Winer, MD, a breast cancer specialist at the Dana-Farber Cancer Institute in Boston, agrees that doctors have a responsibility to share the new findings with their patients.
"For some premenopausal women with estrogen-responsive tumors, this will be another option. But in my view, this is not for all women," he tells WebMD.
Winer notes that while Zometa has been shown to cut the chance of relapse, it has not yet been shown to actually extend lives. And "while not a terribly toxic drug, all drugs have toxicities," he says.
A trial testing Zometa in postmenopausal women recently ended, and those results will be out in a few months, Winer adds. Until those findings are known, the drug should not be given to postmenopausal women, he says.
Breast cancer will be diagnosed in more than 180,000 women in 2008, according to the American Cancer Society. About 20,000 to 25,000 of them will be hormone-fueled tumors in premenopausal women; for now, these are the women who are candidates for Zometa treatment, Winer says.
Avastin Shrinks Advanced Breast Tumors
The researchers studied 736 women, all of whom received Taxotere. Tumors shrank in 63% of those who were also given a high dose of Avastin, 55% of those given a low dose of Avastin, and 44% given a placebo.
The study didn't have enough women to prove that the higher Avastin dose was better than the lower one; however, either dose was significantly better than placebo.
Avastin prevents tumors from growing new blood vessels, thereby choking them to death. It is approved to treat metastatic breast cancer as well as late-stage colorectal cancer and late-stage lung cancer.
Taxotere is a member of a class of chemotherapy drugs called taxanes that that help slow tumor growth by preventing cell division.
The trial was sponsored by Roche, which makes Avastin.