Background: The industry-supported AZURE trial (New England Journal of Medicine 2011;365:1396) showed that the bisphosphonate drug zoledronic acid (ZA), in combination with standard systemic therapy, had no effect on the overall study population of patients with Stage II or III breast cancer. ZA did significantly reduce the risk for recurrence and death among postmenopausal patients.
So, what is the problem? Bisphosphonate therapy has also been linked to osteonecrosis of the jaw, a condition in which there can be exposed bone )most commonly in the mandible, or lower jaw) as well as loose teeth, infections, localized pain, and draining fistulas.
What is the incidence of osteonecrosis? Investigators looked at 3360 women in the AZURE trial. Patients were randomized to get standard systemic therapy, with or without ZA (4mg for 19 doses over 5 years). There were 26 confirmed cases of osteonecrosis, representing a cumulative incidence of 2.1%.
My take: It is comforting that the incidence of jaw necrosis is relatively low. Still, osteonecrosis can be debilitating, and medical treatment with surgical debridement has variable success. If you are offered zoledronic acid or denosumab as a component of your breast cancer management, have a good dialog with your care team about this potential side effect. I’m Dr. Michael Hunter.
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