One of the most common places where breast cancer spreads is the bones, according to the National Cancer Institute. Zoledronic acid and denosumab are two treatments used to preserve bone strength in metastatic breast cancer. Although they have shown to be effective for many people, they do carry side effects and are not for all patients. Consult with your oncologist to see if either of these drugs are appropriate for your situation.
Zoledronic Acid
Zoledronic acid, also known as zoledronate, was approved by the Food and Drug Administration in 2001 and is a type of drug called a bisphosphonate. Drugs.com explains that bisphosphonates prevent the release of calcium from bones. They are used for a variety of purposes, including lowering blood calcium levels, treating cancer that has spread to the bones and preventing or treating osteoporosis in men and postmenopausal women. According to the American Cancer Society, it is administered intravenously over at least 15 minutes. For treating bone tumors, zoledronic acid is typically given once every three to four weeks.
Denosumab
Denosumab was approved by the FDA in 2010 and is typically used with other cancer treatments, such as chemotherapy, to treat cancer that has metastasized to the bones. This drug interferes with a substance called RANK ligand, preventing breakdown of bones and slowing tumor growth, states the American Cancer Society. It also reduces the risk of fractures. This drug is also used in postmenopausal women without cancer to help osteoporosis. Denosumab is administered subcutaneously, which means it is injected under your skin. For individuals with cancer, the drug is given once every four weeks; to treat osteoporosis in healthy populations, it is given less often, according to the American Cancer Society.
Uses in Breast Cancer
When cancer spreads to the bones, it can weaken the bones, increasing the risk of fractures. In women with breast cancer, zoledronic acid and denosumab are used to help reduce the risk of developing weak bones as a result of treatment with aromatase inhibitors, or AIs. AIs block estrogen, and since estrogen helps strengthen bones, a lack of estrogen can lead to osteoporosis, explains the National Cancer Institute. A 2011 study by Robert Coleman et al published in the journal "Cancer" found that not only did zoledronic acid prevent fractures, but women who took this drug also had improved overall survival rates. More research needs to be done to further explore other benefits of zoledronic acid.
Considerations
Both zoledronic acid and denosumab can cause osteonecrosis of the jaw, but this is rare, states the American Cancer Society. This condition damages the bones of the jaw, so tell your doctor if you experience any jaw, mouth or tooth pain while on these drugs. These medications may also harm the kidneys, and your kidney function will be monitored during treatment.
References
- Drugs.com: Zoledronic Acid
- American Cancer Society: Zoledronic Acid
- American Cancer Society: Denosumab
- PubMed.gov: "Cancer"; Zoledronic Acid Use in Cancer Patients: More Than Just Supportive Care?; R Coleman et al; 2011
- National Cancer Institute: Denosumab May Help Prevent Bone Loss
- National Cancer Institute: Metastatic Cancer: Q&A
