According to a recent article published in the Journal of Clinical Oncology, the use of long-term clodronate, a bisphosphonate, may decrease the risk of cancer spread (metastasis) to the bone in patients with operable stages I-III breast cancer during the time patients are treated with the agent.

Breast cancer is diagnosed in over 200,000 women and is responsible for approximately 40,000 deaths annually in the United States. Women with localized, operable breast cancer have a high cure rate and often have long-term survival. However, patients with operable breast cancer are still at risk for metastasis, with the bone being one common site.

Bisphosphonates have been beneficial in treatment of patients with cancer that has already spread to the bone, reducing fractures, pain and hypercalcemia (high calcium levels in the blood). Researchers have been evaluating the effects of bisphosphonates on the prevention of the development of metastasis (spread) of cancer to the bone. Bisphosphonates help prevent bone destruction caused by cancer; however, the exact mechanism through which the prevention of bone metastasis occurs is not clear.

Researchers from England recently conducted a clinical trial evaluating the bisphosphonate clodronate in 1,069 patients with operable stages I-III breast cancer. Patients were treated with either surgery, chemotherapy, radiation therapy and/or hormone therapy, according to their disease characteristics. Half of the patients were treated with clodronate and half of the patients were treated with a placebo (inactive substitute) for two years.

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During the two years while patients were treated with clodronate, only 12 patients treated with clodronate developed bone metastasis, compared to 28 patients treated with placebo. Five years following therapy, however, the rate of patients developing bone metastasis were not significantly different between the two groups, with 63 patients treated with clodronate developing bone metastasis and 80 patients who received placebo developing bone metastasis. At the time of publication of this trial, only 98 patients who were treated with clodronate had died, compared to 129 patients who received placebo. There was no apparent effect of clodronate on the incidence of metastasis for sites other than the bone.

These researchers conclude that clodronate may reduce the risk of developing bone metastasis in patients with operable breast cancer. However, that effect appeared to only be significant during the two years that patients received clodronate. The overall survival was improved in the group of patients treated with clodronate. Future clinical trials further evaluating clodronate in the prevention of bone metastasis in operable breast cancer are warranted, including the optimal duration of use. Patients with operable breast cancer may wish to speak with their physician about the risks and benefits of treatment with clodronate or other bisphosphonates, or the participation in a clinical trial further evaluating the preventive properties of bisphosphonates. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (cancer.gov) and www.eCancerTrials.com. eCancerTrials.com also provides personalized clinical trial searches on behalf of patients.

Reference: Powles T, Paterson S, Kanis JA, et al. Randomized, placebo-controlled trial of clodronate in patients with primary operable breast cancer.

Journal of Clinical Oncology. 2002;20:3219-3224.

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