Friday, September 30, 2011
Zometa for Early-Stage Breast Cancer: Hormones May Matter
Can Zometa (zoledronic acid) prevent recurrence in women with early-stage breast cancer? Today we'll share the latest news and research. Links may be found on the Zometa (zoledronic acid) page of our website.
A new role for Zometa
Zometa is a bisphosphonate often prescribed to prevent bone loss in women taking aromatase inhibitors for breast cancer. It's also used to treat bone metastases in women with stage IV breast cancer.
Recent studies suggest Zometa may also prevent recurrence in women with early-stage breast cancer, but the results have been inconsistent. A new study in the New England Journal of Medicine suggests the key may lie in the hormonal status of the patient.
June: Zometa benefits premenopausal women on Zoladex and hormone therapy
A June 3 study in The Lancet Oncology evaluated Zometa in premenopausal women with hormone-receptor positive, stage I or II breast cancer, who were taking Zoladex (goserelin) for ovarian supression. (Drugs.com covered the study on June 3.)
About half of the 1,803 women took Zometa plus tamoxifen or Arimidex (anastrozole). The rest took tamoxifen or Arimidex alone.
At about 5 years follow-up, more than 2 years after completion of treatment with Zometa, 8% (76/900) of the Zometa group experienced a recurrence, compared to 12% (110/903) of the tamoxifen or Arimidex alone group. There was no significant difference in overall survival. (30 deaths out of 900 women taking Zometa, 43 out of 903 not taking Zometa.)
The authors concluded that the addition of Zometa "improved disease-free survival in the patients taking anastrozole or tamoxifen." They added, "These data show persistent benefits with zoledronic acid and support its addition to adjuvant endocrine therapy in premenopausal patients with early-stage breast cancer."
September: Zometa may only benefit postmenopausal women
In a September 25 New England Journal of Medicine study, about half of the 3,360 women with early-stage breast cancer were treated with Zometa plus standard chemo and hormone therapy. The rest received standard therapy alone. Patients varied in age, menopausal and hormone-receptor status.
In contrast to the Lancet study, at 5 years follow-up, the New England Journal of Medicine study found "no improvement" in disease-free survival for women with early-stage breast cancer taking Zometa. The authors concluded that their findings, "do not support the routine use of zoledronic acid as adjuvant therapy in unselected patients with early-stage breast cancer."
However, when the study participants were evaluated by subgroup, Zometa seemed to benefit postmenopausal women. (Reuters and Medical News Today covered this aspect of the study on September 25.) Zometa improved both disease-free survival (recurrence) rates and overall survival (death) rates for the group who had undergone menopause more than 5 years earlier.
The authors concluded, "For postmenopausal women, the use of bisphosphonates remains appropriate for the prevention of treatment-induced bone loss and osteoporosis and might have beneficial effects on disease outcomes. The optimum schedule, duration, and type of bisphosphonate therapy remain unknown."
Hormonal status may be the key
How do we reconcile these two studies? One found a benefit for premenopausal patients, the other did not. The answer may lie in the hormonal status of the patients.
The New England Journal of Medicine study noted that from a hormonal perspective, the postmenopausal patients in its study were similar to the premenopausal patients in the Lancet study who were treated with Zoladex for ovarian suppression. Both groups "had low levels of reproductive hormones at study entry." The authors suggest that Zometa "operates differently according to menopausal status."
Finally, the authors note that even though chemotherapy may induce menopause in young women, complete ovarian suppression may take "many months." They conclude, "Further investigation into the possible interaction between zoledronic acid and reproductive hormones is required."
At LATESTBreastCancer.com, we'll continue to follow developments in research on Zometa for breast cancer. We'll keep you posted.