What are bisphosphonates?
Bisphosphonates are medicines that are used in the treatment of myeloma bone disease and are usually used in conjunction with other cancer therapy. Bone disease is common in multiple myeloma, with 85% of patients having bone problems.
Bisphosphonates have been shown to:
- Help slow the advancement of bone disease
- Decrease bone pain
- Reduce fractures
- Improve overall survival (one large study)
Bisphosphonates are also used in the treatment of bone metastases and hypercalcemia of malignancy (increased calcium levels in the blood). They are also used in other cancers where the bone is affected (e.g. breast cancer, prostate cancer).
In addition, bisphosphonates are commonly used to treat osteoporosis (bone thinning) and are used in the treatment of a bone disease called Paget’s disease.
Who should take bisphosphonates?
All patients with symptomatic multiple myeloma should receive monthly intravenous bisphosphonate therapy along with their myeloma treatments. Bisphosphonates may also be considered in patients with smoldering multiple myeloma especially among patients demonstrating bone loss in x-rays or in a special bone test that measures bone density (bone densitometry or DEXA).
A large study in the United Kingdom has reported that after 4 years of follow-up both patients with and without bone disease benefitted from Zometa. Both groups had a reduced incidence of skeletal complications. However, it still recommended that only patients with bone disease receive Zometa.
How do bisphosphonates work?
Bisphosphonates block the activity of bone-destroying cells called osteoclasts. Normally, osteoclasts work in harmony with bone-forming cells called osteoblasts in order to rebuild areas of bone that need replacing. However, in myeloma, bone destruction by the osteoclasts is increased and exceeds bone formation, resulting in loss of bone. This can lead to pain, bone fractures, spinal cord compression (a condition where the vertebrae of the spine are compressed putting patients at risk for fractures), and increased levels of calcium in the blood and urine.