Clodronate belongs to a class of drugs called bisphosphonates. Bisphosphonates are agents used to treat or prevent bone complications, such as fractures and/or hypercalcemia (high calcium levels in the blood) in patients with cancer. Some research has indicated that bisphosphonates may prevent the development of metastasis (spread) of cancer to the bone.
Researchers in the UK conducted two randomized, controlled studies to evaluate the effects of clodronate in men with prostate cancer. The Medical Research Council (MRC) PR05 Study included 278 men with metastatic prostate cancer recruited between 1994 and 1998. The MRC PR04 Study also included 471 men with non-metastatic prostate cancer recruited between 1994 and 1997. Men were randomly assigned to oral clodronate or placebo for up to three years if they had metastatic cancer and up to five years if they had non-metastatic disease.
Long-term overall survival was assessed using data from the National Health Service Information Centre. The results indicated that men with metastatic prostate cancer lived significantly longer when treated with clodronate; however, the same effect was not seen in men with non-metastatic disease.
The researchers concluded that clodronate improves survival in men with metastatic prostate cancer who are undergoing hormone therapy; however, clodronate shows no benefit in men with non-metastatic disease.
 Dearnaley DP, Mason MD, Parmar MKB, et al. Adjuvant therapy with oral sodium clodronate in locally advanced and metastatic prostate cancer: Long-term overall survival results from the MRC PR04 and PR05 randomised controlled trials. Lancet Oncology. Published online August 11, 2009.