Survival in patients with carcinomas presenting with bone metastasis at diagnosis: a SEER population-based cohort study.

INTRODUCTION: Carcinoma metastasis to bone is a common reason for consultation to orthopedic surgeons. The presence of bone metastases (BM) is usually associated with poor prognosis which is worsened in the presence of synchronous metastases. The purpose of this study was to: (1) identify the most common carcinomas presenting with BM at diagnosis, to (2) analyze their survival, and (3) compare this against the survival of patients with additional synchronous metastasis based on a large population analysis. MATERIALS AND METHODS: Patients diagnosed with carcinoma between January 2010 and December 2015 were identified from the Surveillance, Epidemiology and End Results (SEER) database. The most common carcinomas presenting with BM at diagnosis were identified. Survival based on the presence of BM and synchronous metastases (lung, brain, liver, lymph nodes) was evaluated with Kaplan-Meier analysis. Five-year survival (%) stratified by carcinoma type was calculated. Hazard ratio (HR) for mortality comparing isolated BM to other synchronous metastases was performed. RESULTS: A total of 4.85% of patients (98,606/2,035,204) with carcinoma presented with BM at diagnosis, most commonly from a lung primary. Five-year survival with isolated BM was lowest in patients with pancreatic carcinoma (5.8%, 95% CI 3.0-9.9%), and highest in patients with breast carcinoma (41.1%, 95% CI 38.6-43.5%). Synchronous metastases increased significantly the risk of mortality within the majority of carcinomas. CONCLUSION: BM at diagnosis has a poor prognosis which is worsened if synchronous metastases are present; a fact to consider when planning orthopedic interventions. LEVEL OF EVIDENCE: Level III, prognostic study.