According to an article recently published in Breast Cancer Research, the use of Clondronate® in the treatment of early breast cancer may reduce the risk of cancer spreading to the bone and may ultimately improve the survival of some patients.
Early breast cancer refers to cancer that has not spread from the breast to distant sites in the body. Standard treatment for early cancer depends on factors such as the extent of spread (for instance, the number of lymph nodes the cancer may have spread to), the age of the patient, hormone status of the patient, as well as biologic factors of the cancer. Typically, however, standard treatment for early breast cancer includes surgery, radiation therapy, chemotherapy, hormone therapy, and/or Herceptin® (trastuzumab).
Although cure rates for early breast cancer remain high, a significant portion of women ultimately experience a cancer recurrence, which may be fatal. A common site of cancer spread (metastasis) is to the bone. Once a patient experiences bone metastasis, their disease is considered incurable; treatment is thus aimed at improving survival and quality of life.
Bisphosphonates, such as Clodronate, have been beneficial in patients with cancer that has already spread to the bone and have effectively reduced 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, it is not clear exactly how bisphosphonates prevent bone metastasis.
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Results from previous studies have indicated that the inclusion of a bisphosphonate in the treatment regimen of patients with early breast cancer reduces their risk of developing bone metastasis and may ultimately improve survival. Research continues to evaluate the use of bisphosphonates in the early stages of cancer.
Researchers from the US, Canada, and Europe recently conducted a clinical trial to further evaluate the use of Clodronate in the treatment of early breast cancer. This trial included 1,069 patients with early breast cancer (stages I-III) who underwent surgery, radiation therapy, chemotherapy, and Nolvadex® (tamoxifen) if they were eligible. Approximately half of the patients were also treated with Clodronate for two years and the other half with placebo (inactive substitute).
Clodronate reduced the risk of developing bone metastasis:
- At 5 years, the risk of developing bone metastasis was reduced by 31% in the group of patients treated with Clodronate compared to those who received placebo.
- During the two years that patients were treated with either Clodronate or placebo, the risk of developing bone metastasis was reduced by 50% for patients with stages II or III breast cancer who were treated with Clodronate.
- There were no significant differences in cancer spread to other internal organs between the two groups of patients.
- Among the women who developed bone metastasis, skeletal events (bone fractures, debilitating pain, surgery, and hospitalization for bone-related issues) were more common among those who received placebo (73%) versus those treated with Clodronate (57%).
- Survival rates were greater among women treated with Clodronate.
- There were no severe side effects associated with Clodronate; diarrhea was the most common side effect associated with Clodronate.
The researchers concluded that these results add to findings indicating that the use of a bisphosphonate such as Clodronate in the treatment of early breast cancer appears to reduce the risk of bone metastasis and may affect survival in some patients. Further study is necessary to determine how to incorporate bisphosphonates into the treatment of earlier stages of cancer.
Reference: Powles T, Paterson A, McCloskey E, et al. Reduction in bone relapse and improved survival with oral clodronate for adjuvant treatment of operable breast cancer. Breast Cancer Research. 2006; 8.doi:10.1186/bcr1384.