Osteonecrosis of the jaw in patients with multiple myeloma during and after treatment with zoledronic acid

BACKGROUND AND OBJECTIVE: To analyze the incidence, the clinical features, and the factors associated with the development of osteonecrosis of the jaw (ONJ) in patients with multiple myeloma (MM) treated with zoledronic acid. PATIENTS AND METHOD: Sixty-four patients diagnosed with MM and treated with zoledronic acid between August 1996 and March 2006 were included. Demographic data, predisposing factors, the type of antineoplastic therapy received and the infusions of biphosphonate were recorded. The main characteristics of the seven patients with ONJ, including clinical and physical examinations data, diagnostic methods and treatment established were reported. RESULTS: The overall incidence of ONJ was 7 out of 64 patients (10.93%). A recent oral surgical procedure has been associated with the ONJ (p < 0.0001). The mean of infusions of zoledronic acid before onset of osteonecrosis (standard deviation) was 30 (7.04) in contrast to 19.5 (11.8) cycles (p = 0.03) in the patients who did not present this complication. The cumulative risk increased from 6.7% after 20 treatments with zoledronic acid up to 31.7% at 36 infusions. Three patients exhibited ONJ after discontinuing zoledronic acid. CONCLUSIONS: The ONJ in patients with MM who underwent dental or oral surgery appears to be associated with long term exposure to zoledronic acid. The long-lasting bone effect of biphosphonate could explain the appearance of osteonecrotic lesions after discontinuing treatment with biphosphonate.