Bone-directed Therapy for Breast Cancer in Men
When breast cancer spreads to the bones, it can cause problems like pain, fractures (breaks), and high blood calcium levels. Drugs like bisphosphonates and denosumab can lower the risks of these problems happening, and so are often used to treat patients with breast cancer that has spread to bones.
Bisphosphonates are drugs that are used to help strengthen bones and, reduce the risk of fractures, and pain in bones that have been weakened by metastatic breast cancer. The most common bisphosphonates used in breast cancer patients are pamidronate (Aredia®) and zoledronic acid (Zometa®). They are given intravenously (IV).
Bisphosphonates may also help against bone thinning (osteoporosis) from treatment with aromatase inhibitors and LHRH analogs (see “ Hormone therapy for breast cancer in men”). There are a number of medicines, including some oral forms of bisphosphonates, to treat loss of bone strength when it is not caused by cancer spread to the bones.
Bisphosphonates can have side effects, including flu-like symptoms and bone pain. They can also lead to kidney problems, so patients with poor kidney function may not be able to be treated with these drugs.
A rare but very distressing side effect of bisphosphonates is damage (osteonecrosis) in the jaw bones or ONJ. It can be triggered by having a tooth removed while getting treated with the bisphosphonate. ONJ often appears as an open sore in the jaw that won't heal. It can lead to loss of teeth or infections of the jaw bone.
Doctors don't know why this happens or the best way to treat it, other than to stop taking bisphosphonates. Maintaining good oral hygiene by flossing, brushing, making sure that dentures fit properly, and having regular dental checkups may help prevent this. Your cancer doctor will likely recommend that you have a dental checkup and have any tooth or jaw problems treated before you start taking a bisphosphonate.
Denosumab (Xgeva®, Prolia®) is another drug that can help lower the risk of fractures and other problems caused by breast cancer that has spread to the bone. It works differently from bisphosphonates. In studies of patients with breast cancer that had spread to the bone, it seemed to help prevent problems like fractures (breaks) better than zoledronic acid (Zometa). It also can help even after bisphosphonates stop working.
In patients with cancer spread to bones, this drug is injected under the skin every 4 weeks. Side effects include low blood levels of calcium and phosphate, as well as the jaw bone problem known as osteonecrosis of the jaw. This drug does not seem to affect the kidneys, so it is safe to take if you have kidney problems.
Denosumab can also be used to strengthen weak bones if you are given treatments that lower androgen levels. This use has been studied in men being treated for prostate cancer, but it isn’t likely to be studied for this use in male breast cancer since this disease is so rare. When given for this purpose, denosumab is given less often (usually every 6 months).
Last Medical Review: October 10, 2014 Last Revised: January 26, 2016
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