Surprising results from a recent clinical trial published in the
Journal of Clinical Oncology indicate that the use of clodronate has no long-term benefits for patients with advanced breast cancer.
Breast cancer is a common malignancy occurring in women in the United States, with almost 200,000 new cases diagnosed each year. Advanced breast cancer refers to cancer that has spread from its site of origin to distant sites in the body (metastasis), often involving lymph nodes, vital organs and/or bones. Approximately 70% of women with advanced breast cancer will experience a spread of their primary cancer to their bones during their lifetime.1
Bisphosphonates are a type of drug that have been shown to reduce the development and/or progression of bone metastases in patients with advanced breast cancer. The exact mechanism through which bisphosphonates produce these effects has not been clearly elucidated. Clodronate is an agent classified as a bisphosphonate that is not yet approved for clinical use and is still in the process of being evaluated in clinical trials.
To date, only one previous clinical trial has been conducted to examine the effects of clodronate utilized in the adjuvant setting (following primary treatment) in patients with advanced breast cancer. This trial analyzed the effects of clodronate 3 years following patient treatment and indicated that clodronate did reduce the development and progression of bone metastases in advanced breast cancer patients.2,3
Now, the most recent results from a clinical trial evaluating long-term effects of clodronate have just been published. This trial involved nearly 300 patients with advanced breast cancer who either received clodronate or a placebo (inactive substance) as adjuvant therapy for 3 years. Five years following treatment, patient data was analyzed to reveal the potential indications of clodronate for this group of patients. Surprisingly, bone metastases were found equally between the two groups of patients. Moreover, patients receiving clodronate had a higher incidence of cancer recurrence not involving the bones (43%) than the placebo group (25%). Overall survival was 70% for patients receiving clodronate and 83% for patients receiving the placebo. Disease-free survival was also significantly lower in the group receiving clodronate (56%) versus the group receiving the placebo (71%).
These results appear to indicate that adjuvant clodronate does not prevent or reduce the development or progression of bone metastases in patients with advanced breast cancer. In addition, results from this trial indicate that clodronate may have a negative effect on long-term overall survival and disease-free survival. However, results from future clinical trials are needed in order to derive a definitive conclusion (Journal of Clinical Oncology, Vol 19, No 1, pp 10-17, 2001)
1 Coleman et al. Breast Journal Cancer, Vol 55, pp 61-66, 1987.
2 Saarto et al. Journal of Clinical Oncology, Vol 15, pp 1341-1347, 1997.
3 Saarto et al. Breast Journal Cancer, Vol 75, pp 602-605, 1997.