Prevalence of primary malignant tumours, rates of pathological fracture, and mortality in the setting of metastatic bone disease

The modern prevalence of primary tumours causing metastatic bone disease is ill-defined in the oncological literature. Therefore, the purpose of this study is to identify the prevalence of primary tumours in the setting of metastatic bone disease, as well as reported rates of pathological fracture, postoperative complications, 90- day mortality, and 360- day mortality for each primary tumour subtype.Methods The Premier Healthcare Database was queried to identify all patients who were diagnosed with metastatic bone disease from January 2015 to December 2020. The prevalence of all primary tumour subtypes was tabulated. Rates of long bone pathological fracture, 90- day mortality, and 360- day mortality following surgical treatment of pathological fracture were assessed for each primary tumour subtype. Patient characteristics and postoperative out-comes were analyzed based upon whether patients had impending fractures treated prophy-lactically versus treated completed fractures.Results In total, 407,893 unique patients with metastatic bone disease were identified. Of the 14 primary tumours assessed, metastatic bone disease most frequently originated from lung (24.8%), prostatic (19.4%), breast (19.3%), gastrointestinal (9.4%), and urological (6.5%) malignancies. The top five malignant tumours resulting in long bone pathological fracture were renal (5.8%), myeloma (3.4%), female reproductive (3.2%), lung (2.8%), and breast (2.7%). Following treatment of pathological fractures of long bones, 90- day mortality rates were greatest for lung (12.1%), central nervous system (10.5%), lymphoma (10.4%), gastro-intestinal (10.1%), and non- renal urinary (10.0%) malignancies. Finally, our study demon-strates improved 90- day and 360- day survival in patients treated for impending pathological fracture compared to completed fracture, as well as significantly lower rates of deep vein thrombosis, pulmonary embolism, urinary tract infection, and blood transfusion.Conclusion This study defines the contemporary characteristics of primary malignancies resulting in metastatic bone disease. These data should be considered by surgeons when prognosticat-ing patient outcomes during treatment of their metastatic bone disease.