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Clodronate showed modest reduction of metastases in postmenopausal women
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San Antonio Breast Cancer Symposium
SAN ANTONIO — The bisphosphonate clodronate was associated with a low incidence of adverse events and toxicity among patients with breast cancer, according to study results presented here.
There was also a modest reduction in the incidence of distant metastases in postmenopausal women who received the drug.
“This reduction was smaller than we had hoped for and was not statistically significant,” said study researcher Alexander H.G. Paterson, MD, professor in the departments of medicine and oncology at the University of Calgary in Canada. “Although clodronate appeared more favorable for all endpoints, only the comparisons of the distant metastasis-free interval and nonskeletal metastasis-free interval were statistically significant and favorable for the clodronate patients.
Paterson and colleagues conducted the NSABP B-34 trial, a prospective, randomized, double blind, phase 3 trial of 3,323 patients with stage I, II or III breast cancer. Patients were randomly assigned to oral clodronate 1,600 mg for 3 years or placebo, given alone or in addition to adjuvant chemotherapy or hormone therapy. The median follow-up was 7.6 years.
The number of patients who experienced death or cancer recurrence was 286 in the clodronate group vs. 312 in the placebo group, for a relative reduction of about 9%. The researchers observed relative reductions of 23% for the occurrence of skeletal metastases and 26% for nonskeletal metastases. Results also showed that clodronate may perform better in patients aged 50 years and older at breast cancer diagnosis, and for women with ER/PR-positive nodes.
“At this point, clinical indications are not absolute, but a tolerable agent that has a known beneficial effect on osteopenia with a small reduction in distant disease recurrence may be of interest to some patients and clinicians,” Paterson said.
Disclosure: Dr. Paterson has received grant/research support from Amgen and is a consultant for Amgen, Roche and GlaxoSmithKline.
Earn CME this spring at the HemOnc Today Breast Cancer Review & Perspective meeting to be held March 23-24, 2012 at the Hilton San Diego Bayfront. See details at HemOncTodayBreastCancer.com.
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Clodronate is a weaker bisphosphonate than zoledronic acid. In this trial, they chose people at lower risk for recurrence, so it took a long time to have enough events to determine the drug’s benefit. If you look at the data, they didn’t have that many events. After 8 years, they found no statistically significant difference overall. If you look at women aged older than 60 years, the truly postmenopausal women, there appeared to be benefits in DFS and, possibly, OS. The clodronate results are consistent with results we’ve seen in other studies. The benefits of adjuvant bisphosphonates are real, but they are likely limited to women who have suppressed estrogen. This is yet another trial that shows those benefits.
Adam M. Brufsky, MD, PhD
HemOnc Today Editorial Board member
For more information:
- Paterson A. #S2-3. Presented at: the 2011 CTRC-AACR San Antonio Breast Cancer Symposium; Dec. 6-11, 2011; San Antonio.
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