Bisphosphonate-associated osteonecrosis: a clinician's reference to patient management.
Bisphosphonates (BPs), as inhibitors of osteoclasts, are widely used in the management of metastatic bone disease and in the prevention of osteomalacia and osteoporosis. Recent cases of bone necrosis of the jaws have been associated with the use of bisphosphonate therapy. A case is presented of a patient with osteonecrosis of the maxilla with a history of long-term bisphosphonate therapy for metastatic breast cancer. The authors treated the patient and suggest appropriate patient management guidelines with reference to current knowledge. Although a definitive treatment for bisphosphonate-associated osteonecrosis has not yet been established, clinicians must be aware of the pharmacologic properties of several bisphosphonates currently available and their indications, susceptible risk factors in the development of osteonecrosis of the jaws, the clinical signs and symptoms, and recommendations for patient management, including prevention and early recognition. BPs, potent inhibitors of osteoclast-mediated bone resorption, were first introduced more than 20 years ago. Since then, they have been used widely in the management of bone diseases, including hypercalcemia related to malignancy, myeloma-related bone disease, Paget's disease and osteoporosis. They have also been shown to inhibit tumor cell proliferation and inhibit angiogenesis. These additional features have made BPs useful in the treatment of metastatic disease, including breast and prostate cancer, resulting in a rise in the medical use of these drugs. However, recent reports suggest that BPs, particularly the nitrogen-containing BPs pamidronate (Aredia) and zoledronic acid (Zometa), both manufactured by Novartis of East Hanover, NJ, are capable of causing bisphosphonate-associated osteonecrosis of the jaw (BON). With 2.5 million patients treated with pamidronate and/or zoledronate worldwide, BON occurs in about one per 10,000 treated patients (Novartis, unpublished data, 2004). Currently, the total number of reported cases associated with alendronate (Fosamax, Merck and Co. Inc., White-house Station, NJ) the most commonly prescribed oral bisphosphonate, is approximately 170 worldwide (C. Arsver, oral communication, March 2006). This corresponds to a spontaneous BON incidence of approximately 0.7 cases per 100,000-years exposure. However, there is insufficient data to determine why the osteonecrosis reported seems to particularly affect the jaw, with a slightly higher rate in the mandible than the maxilla. This report concerns the management of a patient with BON. Information provided includes: the pharmacologic properties of the several bisphosphonates currently available; the pathobiological mechanism; the clinical presentation of the oral lesions; and recommendations for the oral management of patients who have received BP therapy, with consideration of a preventative approach based on current knowledge.
Grewal
Varinder S
VS
vgdds@hotmail.com
Fayans
Edgar P
EP