Ehrenstein V, Heide-Jørgensen U, Schiødt M, et al. - In the present study, the researchers sought to estimate incidence proportions and incidence rates of osteonecrosis of the jaw (ONJ) in cancer patients with bone metastases from solid tumors treated for the prevention of skeletal-related events in routine clinical practice. This cohort study, which took place in Denmark, Norway, and Sweden between 2011 and 2018, included 3 treatment cohorts: a denosumab inception cohort (DEIC), a zoledronic acid inception cohort (ZAIC), and a denosumab-switch cohort (DESC). The DEIC contained 1,340 patients, the ZAIC contained 1,352 patients, and the DESC contained 408 patients. Data reported that the 5-year incidence proportions of ONJ were 5.7% in the DEIC, 1.4% in the ZAIC, and 6.6% in the DESC. It was noted that the corresponding ONJ incidence rates per 100 person-years were 3.0, 1.0, and 4.3. Prostate cancer patients and Denmark had the highest incidence proportions and rates. This study estimates the risk of medically confirmed ONJ in patients starting denosumab or zoledronic acid in routine clinical practice across 3 Scandinavian countries. The outcomes differed depending on the cancer site and the country.