Temporal trends in gastric cancer incidence by age and sex in the United States.

Abstract

e16130 Background: The overall incidence of gastric cancer has declined in the United States over recent decades. However, emerging evidence suggests that these aggregate trends may obscure important demographic heterogeneity. Rising incidence among younger adults has been reported, but the magnitude, direction, and demographic specificity of these changes remain incompletely characterized. A comprehensive evaluation of long-term incidence trends across age, sex, and race is needed to identify subpopulations with disproportionate increases in gastric cancer incidence and to inform future etiologic and prevention-focused research. Methods: We conducted a population-based trend analysis using SEER data from 2000–2022. Cases of microscopically confirmed malignant gastric cancers were included with no histological restrictions. Age-adjusted incidence rates (per 100,000) were standardized to the 2000 U.S. standard population. Temporal trends were quantified using annual percent change (APC) with robust 95% confidence intervals (CI). Age-stratified analyses compared younger adults (20–49 years) with older adults (≥50 years). Interaction tests assessed heterogeneity in temporal trends by age group, sex, and race. Analyses were performed using SEER*Stat and R (v4.5.2). Results: 142,606 total gastric cancer cases were identified. Overall incidence declined significantly over the study period (APC −0.59%; 95% CI −0.78 to −0.40; p = 1.6×10⁻⁹). Incidence among adults aged ≥50 years (n = 126,495) declined significantly (APC −0.79%/; 95% CI −1.25 to −0.32; p = 0.0009). In contrast, among adults aged 20–49 years (n = 15,967), incidence increased from 1.78 to 2.22 per 100,000 (+24.7%), corresponding to an APC of +1.01% (95% CI +0.55 to +1.48; p = 1.6×10⁻⁵) with strong evidence of divergence between age groups (interaction p = 7.06×10⁻⁸). Further sex-stratified analyses in the young adult group demonstrated that incidence among females aged 20-49 increased significantly (APC +2.29% per year; 95% CI 1.75 to 2.83; p = 3.65×10⁻¹⁷), whereas no significant change was observed among males aged 20-49 (APC −0.06%; 95% CI −0.49 to 0.38; p = 0.795), with significant sex-based heterogeneity (interaction p = 2.61×10⁻¹¹). Conclusions: Despite an overall decline in gastric cancer incidence, the rates are increasing among younger adults, mostly driven by increasing incidence in young females based on our study. These divergent trends suggest distinct and evolving risk profiles in early-onset gastric cancer that are not captured by aggregate population statistics. Further research into age-specific etiologic factors and targeted prevention strategies is warranted. Group N APC (% per yr) 95% CI p-value Overall 142,606 −0.59 −0.78 to −0.40 1.6×10⁻⁹ Age ≥50 126,495 −0.79 −1.25 to −0.32 9.0×10⁻ 4 Age 20–49 15,967 +1.01 +0.55 to +1.48 1.6×10⁻⁵ Male, 20–49 8,570 −0.06 −0.49 to +0.38 0.795 Female, 20–49 7,316 +2.29 +1.75 to +2.83 3.65×10⁻¹⁷