jaw (ONJ) affects patients with cancer and metastatic bone disease (MBD) treated with bone-modifying agents (BMAs), yet the true incidence is unknown.OBJECTIVE To define the cumulative incidence of ONJ at 3 years in patients receiving zoledronic acid for MBD from any malignant neoplasm.DESIGN, SETTING, AND PARTICIPANTS This multicenter, prospective observational cohort study (SWOG Cancer Research Network S0702) included patients with MBD with either limited or no prior exposure to BMAs and a clinical care plan that included use of zoledronic acid within 30 days of registration. Medical, dental, and patient-reported outcome forms were submitted at baseline and every 6 months. Follow-up was 3 years. Osteonecrosis of the jaw was defined using established criteria.