National trends in mortality from gastric cancer with metastatic involvement of the digestive and respiratory systems in the United States.

e15694 Background: Gastric cancer remains a major contributor to cancer-related mortality in the United States (US), particularly in advanced stages. However, long-term national trends and sociodemographic disparities in mortality associated with metastatic involvement of the respiratory (RS) and digestive systems (DS) remain incompletely characterized. Methods: We conducted a national population-based analysis using the CDC WONDER Multiple Cause of Death database, including individuals aged ≥45 years from 1999–2023. Deaths with GC as the underlying cause (ICD-10 C16) and secondary metastases of the RS and DS as contributing causes (ICD-10 C78) were identified. Age-adjusted mortality rates (AAMRs) per 100,000 population were calculated and stratified by age, sex, race, ethnicity, geographic region, and urbanization. Temporal trends were evaluated using Joinpoint regression to identify inflection points and estimate annual percent change (APC) and average annual percent change (AAPC). Results: Our analysis showed that a total of 18,885 deaths were attributed to GC with metastatic involvement of the RS and DS, corresponding to an AAMR of 1.5 per 100,000. National mortality demonstrated a U-shaped temporal pattern, with a significant decline from 1999 to 2008 (APC -8.1%; 95% CI [-9.2; -6.9]), followed by a sustained increase through 2023 (APC +3.4%; 95% CI [2.6; 4.2]). Among individuals aged ≥ 65 years, mortality declined significantly during the early study period (APC -8.3%; 95% CI [-11.6; -6.2]), before reversing after 2008 (APC 3.9%; 95% CI [2.7; 5.7]). Both men and women exhibited similar trend reversals, with significant post-2008 increases (men: APC 5.7%; 95% CI [4.3; 10.4], and women: APC 5.9%; 95% CI [4.6; 8.2]. Racial and ethnic disparities persisted throughout the study period. Non-Hispanic Black and Asian/Pacific Islander populations demonstrated higher AAMRs and steeper post-inflection increases compared with non-Hispanic White populations, with a post-2008 APC range approximately 4.0% to 6.5%. Urbanization analyses revealed significantly increasing mortality in large central metropolitan areas (APC 4.7%, 95% CI [3.6; 6.2]), whereas nonmetropolitan regions exhibited declining mortality (AAPC -1.05%; 95% CI [-1.9; -0.2]). Conclusions: After a decade of declining mortality, deaths associated with metastatic GC involving the RS and DS have risen steadily in the US since the late 2000s. This reversal disproportionately affects older adults, ethnic minority populations, and residents of large metropolitan areas, highlighting widening inequities in advanced disease outcomes. These findings suggest that prior gains in GC mortality have not been sustained and underscore the need for targeted strategies focused on earlier detection, equitable access to specialized care, and improved management of advanced disease in high-risk populations.