Burden and trends of early-onset gastric cancer in the 11 BRICS countries (2025 expansion): 1990-2021 with projections to 2035.

[OBJECTIVES] Gastric cancer (GC) ranks as the fifth most common malignancy and the fifth leading cause of cancer-related deaths globally. Early-onset GC (EOGC), accounting for approximately 10% of all GC cases, remains understudied regarding disease burden trends across the 11 BRICS nations. Leveraging the Global Burden of Disease (GBD) 2021 database, this study analyzes the incidence, burden trends, and attributable risk factors of EOGC in the 11 BRICS countries (2025 expansion) and projects its epidemiological trajectory from 2022 to 2035.

[METHODS] Data were obtained from the GBD 2021 database. We assessed the EOGC incidence and burden in the 11 BRICS countries (2025 expansion) using both absolute numbers and age-standardized rates (ASRs). Joinpoint regression analysis was used to identify significant temporal trends in ASRs from 1990 to 2021. Health inequality analysis revealed health inequality patterns in EOGC burden associated with the socio-demographic index (SDI). Decomposition analysis was performed to identify key drivers of EOGC burden variations across the 11 BRICS nations. Additionally, we analyzed trends in population attributable fractions (PAFs) and summary exposure values (SEVs) for relevant risk factors, projected EOGC incidence and burden for 2022-2035 using the BAPC model, and evaluated the sensitivity of each indicator's prediction results using the mean absolute difference (MAD) following secondary prediction with the Nordpred model.

[RESULTS] From 1990 to 2021, the 11 BRICS countries experienced an 11.87% decline in absolute EOGC cases and a 33.75% reduction in disability-adjusted life years (DALYs). In 2021, China and India exhibited the highest absolute burden, while the United Arab Emirates (UAE) had the lowest. The ASRs were highest in China and Russia and lowest in the UAE. A male predominance in EOGC burden was observed, except in Ethiopia, the UAE, and Saudi Arabia. Joinpoint regression revealed declining trends in age-standardized incidence rates (ASIR) and age-standardized DALY rates (ASDR) across all nations except Egypt (average annual percentage changes [AAPC] = 0.40, 95% confidence interval [CI]: 0.26-0.50; AAPC = 0.10, 95% CI: - 0.02-0.20). Ethiopia demonstrated the most substantial ASIR reduction, while the Russian Federation indicated the most significant ASDR decline. Transient increases (annual percentage change [APC] > 0, 95% CI excluding 0) occurred in South Africa (1990-2004) and Saudi Arabia (2003-2008). Health inequality analysis indicated persistent relative inequalities concentrated in high-SDI countries (concentration index > 0, 95% CI excluding 0), though absolute inequalities were non-significant (95% CI of slope index including 0). Decomposition analysis identified population growth and aging as primary drivers of increasing burden, except in China and Russia (population growth) and Ethiopia (aging). Epidemiological changes correlated with burden reduction, except in Egypt. Risk factor analysis indicated declining smoking-attributable PAFs in most countries, with increases in Indonesia and Iran. The Russian Federation (15.52%, 95% uncertainty interval [UI]: 0.18.49-12.52%) and China (14.13%, 95% UI: 20.11-9.97%) exhibited the highest smoking PAFs, with notable SEV increases in the Russian Federation (11.95%) and Egypt (9.13%). High-sodium diet PAFs remained stable, peaking in India (11.57%, 95% UI: 0-57.36%) and Ethiopia (11.49%, 95% UI: 0-65.27%), with significant SEV rises in India (6.32%) and Egypt (2.60%). Projections suggest overall EOGC burden reduction across the 11 BRICS nations, though South Africa's ASDR is predicted to rise to the second highest by 2035.

[CONCLUSION] While the overall EOGC burden has declined across the 11 BRICS nations (2025 expansion), member states face distinct epidemiological challenges. Higher-SDI nations and Males bore heavier burdens. Smoking and high-sodium diets were key modifiable risks. By 2035, China and India will face the highest burdens, while South Africa's ASDR will rise. We recommend enhanced regional collaboration -including shared best practices, joint prevention strategies, and harmonized data collection-to address these persistent public health concerns, strengthen future surveillance, and improve comparative analyses.