Global trends in gastric cancer burden among adolescents and young adults: A population-based observational study...

Gastric cancer (GC) in adolescents and young adults (AYA; 15-39 years) is rare but clinically distinct. Contemporary global estimates and temporal drivers - particularly age-period-cohort (APC) effects and socioeconomic differentials - remain unclear. We conducted a secondary analysis using data from the Global Burden of Disease 2021 database and quantified the incidence, mortality, and disability-adjusted life years of AYA GC across 204 countries and territories from 1990 to 2021. Age-standardized rates and estimated annual percentage changes (EAPCs) were calculated using log-linear regression. APC models were used to describe age-, period-, and cohort-related patterns. Disease burden was stratified by Socio-demographic Index (SDI), and Global Burden of Disease (GBD)-attributed deaths related to diets high in sodium and smoking were examined within the GBD comparative risk assessment framework. From 1990 to 2021, the global AYA GC burden declined substantially, yet disparities by sex, SDI, and cohort persisted. Globally, the age-standardized incidence rate of AYA GC decreased from 2.45 per 1,00,000 population in 1990 to 1.41 per 1,00,000 population in 2021, with an EAPC of -2.04% (95% confidence interval [CI]: -2.21 to -1.88). Deaths declined from 38.15 × 103 to 24.27 × 103, with an EAPC of -2.75% (95% CI: -2.94 to -2.57). The age-standardized disability-adjusted life year rate decreased from 99.73 to 46.64 per 1,00,000 population, with an EAPC of -2.54% (95% CI: -2.63 to -2.46). Males consistently had higher burdens than females. Incidence was positively correlated with SDI over time (r = 0.2393, P < .001), whereas mortality was negatively correlated with SDI in the 2021 cross-sectional analysis (r = -0.3092, P < .001). APC analysis showed a positive age effect peaking at 35 to 39 years and a net drift of -2.18% per year. Within the GBD comparative risk assessment framework, the GBD-attributed proportion of AYA GC deaths related to diets high in sodium was approximately 15% in East Asia in 2021, while the GBD-attributed proportion related to smoking exceeded 10% in parts of Central and Eastern Europe.