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.
