Premenopausal women undergoing chemo for breast cancer may benefit from osteoporosis drug

A multicenter, Phase III study conducted by researchers at Columbia University Medical Center showed that the osteoporosis drug zoledronic acid (Zometa) prevents bone loss in premenopausal women followed for 12 months undergoing chemotherapy following surgery for early-stage breast cancer. This is the first study to evaluate the use of the drug in premenopausal breast cancer patients, but previous studies have shown that similar drugs prevent bone loss during and following chemotherapy in this group.

Zoledronic acid has been shown to prevent bone loss in postmenopausal women, and recent findings have indicated that it reduces risk of recurrence in women with breast cancer.

“Our study confirms that women experience significant bone loss due to cancer treatments and that zoledronic acid can prevent this loss,” said Dawn L. Hershman, MD, MS, assistant professor of medicine at Columbia University’s College of Physicians and Surgeons and the study’s lead author. “While our findings are promising, it’s too early for us to recommend this drug for all premenopausal women undergoing chemotherapy for breast cancer because we don’t yet have all the information we need on dosing, cost effectiveness, and whether this drug actually prevents bone fractures. However, this research does show we need to be more vigilant about monitoring patients’ bone densities before and during treatment so we can protect bone health and offset bone fracture or osteoporosis risk.”

• Randomized, double-blind, multicenter phase III trial comparing treatment with zoledronic acid or placebo every three months for one year; 101 patients were enrolled in the trial and 85 completed it. 
• All patients in the trial were given oral vitamin D and calcium supplements. 
• Primary measure of bone loss was change in bone mineral density (BMD), measured via scans of the lower spine and hip. Scans were performed prior to chemotherapy and at six and 12 months. 
• Patients who received zoledronic acid had stable BMDs at both six and 12 months. Patients who received placebo showed a significant decline in spine BMD: 2.4 percent at six months and 4.1 percent at 12 months. In the hip, BMD declines were 0.8 percent at six months and 2.6 percent at 12 months. 
• Side effects did not differ significantly between the two groups.

About 55,000 women under the age of 55 are diagnosed with breast cancer each year, and many are treated with chemotherapies that can temporarily or permanently induce oestrogen deficiency and early menopause. Because oestrogen is critical for building and maintaining bone mass, the longer a woman is oestrogen deficient, the higher her risk for long-term bone loss. In addition, bone loss can be further exacerbated by some subsequent hormonal therapies, such as ovarian suppression. Extrapolated over the standard five to 10 year treatment period for breast cancer, the researchers say women with breast cancer undergoing early menopause could sustain a bone loss of more than 20 percent, which may put them at increased risk for bone fractures.

The Journal of Clinical Oncology is the tri-monthly peer-reviewed journal of the American Society of Clinical Oncology (ASCO), the world’s leading professional society representing physicians who treat people with cancer.

(Source: Journal of Clinical Oncology: Columbia University: August 2008)