Evolving mortality patterns of bone metastasis in older adults with common primary cancers in the US.

549 Background: Secondary malignant neoplasms of bone and bone marrow (SMNBBM) represent a significant source of morbidity. This study aimed to evaluate its mortality trends in U.S. adults aged ≥65, alongside incidence and mortality trends of the three primary cancers most commonly associated with bone metastasis. Methods: This observational study used CDC WONDER Multiple Cause of Death data (1999–2023) and US Cancer Statistics incidence data. We assessed temporal trends in SMNBBM-related (ICD-10: C79.5) mortality, stratified by demographics, primary site of malignancy, and geography. Incidence and mortality trends, regardless of metastatic status, for prostate, lung and bronchus, and breast cancers were also analyzed. Age-adjusted mortality and incidence rates (AAMRs, AAIRs) and crude mortality rates (CMRs) were calculated per 100,000. Annual and average annual percent changes (APC, AAPC) were estimated using Joinpoint regression. Results: From 1999 to 2023, a total of 293,425 SMNBBM-related deaths occurred. The overall AAMR was 27.2, with the highest rates observed among males (38.4), Whites (28.3), rural residents (26.8) and those aged ≥85 (41.9). Regionally, the West had the highest AAMR (29.8), though Arkansas, in the South, reported the highest nationally (55.8). SMNBBM-related mortality significantly increased over time (AAPC: 2.4%; 95% CI: 2.3 to 2.6), despite declining mortality for primary prostate, lung, and breast cancers irrespective of metastatic status (AAPCs: -2.2%, -2.1%, and -1.0%, respectively). Among deaths with SMNBBM and a primary cancer, prostate cancer had the highest AAMR (15.8), followed by lung and bronchus (7.7) and breast (7.0). Prostate cancer also had the highest incidence rate (701.7), while lung and bronchus cancer had the lowest among these three primary sites (350.9). Conclusions: There is a growing burden of SMNBBM–related mortality in elderly cancer patients, particularly among high-risk subgroups. This occurs despite overall improvements in primary cancer outcomes and declining trends in incidence and non-metastatic mortality. These findings suggest a shifting survivorship landscape and highlight the need for enhanced long-term surveillance and bone-targeted interventions.