- SATURDAY, May 31 (HealthDay News) — A drug used to treat
osteoporosis lowered the risk of breast cancer recurrence in premenopausal
women with early breast cancer.

The Austrian researchers also found that women who took Zometa
(zoledronic acid) had a 30 percent lower risk of the cancer spreading to
the bone, with other benefits as well.

“We found not only an effect on bone metastases, which one might have
anticipated, but also on local regional recurrence, distant bone
metastases and contralateral breast cancer,” said study author Dr. Michael
Gnant, a professor of surgery at the Medical University of Vienna. “The
indication is that zoledronic acid exerts a benefit through a variety of
mechanisms which, all together, create a tumor-hostile environment…”

Gnant, who presented his findings this weekend at the American Society
of Clinical Oncology annual meeting in Chicago, spoke at a Saturday news
conference. The trial was partially supported by Novartis, which makes
Zometa.

Earlier studies had indicated that Zometa can reduce bone loss
occurring as a result of cancer treatment, and that it might also have an
effect on the cancer itself.

For this trial, researchers randomized 1,803 patients to one of four
arms: hormone therapies tamoxifen or Arimidex (anastrozole, an aromatase
inhibitor), with or without Zometa.

Tamoxifen stops estrogen from reaching cancer cells while Arimidex
interferes with actual production of estrogen. The hormone estrogen fuels
breast cancer cells in estrogen-receptor positive tumors.

All patients were undergoing drug-induced ovarian suppression (to stop
production of estrogen), had had surgery to remove the primary tumor, and
had seen the cancer spread to 10 or fewer lymph nodes. Treatment lasted
three years.

After a median follow-up of five years, either hormone therapy plus
Zometa reduced the risk of relapse by 36 percent compared with hormone
therapy alone. There were no unanticipated side effects, and the drugs
were generally well-tolerated.

“The overall outcome of patients in this trial was excellent,” Gnant
said. “This is reassuring that patients with endocrine [hormone]-response
disease, even in premenopause, can be safely treated with adjuvant
chemotherapy. The benefit was seen in and outside the bone.”

Although about 5 percent of participants had had chemotherapy before
surgery to shrink the tumor, none received later chemo. In Europe, breast
cancer patients are commonly treated with endocrine therapy alone,” said
Dr. Joanne Mortimer, vice chairwoman of medical oncology at City of Hope
Cancer Center in Duarte, Calif. In the United States, some, but not all,
women in this group are treated without chemotherapy.

“This is not a trial about hormones instead of chemo. It's about
Zometa,” Mortimer said. “We know that this drug improves bone health, but
there is also some evidence that it may actually have an effect on cancer
cells, and the fact that this was seen in this population is very
exciting.”

“This is going to open up a new opportunity for patients, and also for
further research,” said Dr. Edith Perez, chairwoman of the breast cancer
clinic at the Mayo Clinic in Jacksonville, Fla. “It has some limitations
in that it was done only in premenopausal women, but it is consistent with
other studies that have been reported with other drugs in that same
class.”

A national study is now looking at both pre- and postmenopausal women
and Zometa, Perez added.

More information

The American Society of Clinical Oncology has more
information on breast cancer.