Supplementary file 1_Epidemiological trends and risk factors of early-onset colorectal cancer in the founding BRICS countries, 1990–2023, with projections to 2050.zip

A Bayesian Age–Period–Cohort (BAPC) model projected trends to 2050. External corroboration was performed in a retrospective cohort of 236 CRC patients from a tertiary hospital in China using logistic and Cox regression analyses.</p>Results<p>In 2023, China had the highest age-standardized incidence rate (ASIR) of EOCRC (3.83/100,000), while India had the lowest (1.26/100,000). From 1990–2023, Brazil showed the fastest ASIR increase (EAPC = 1.72), whereas China declined (EAPC =-1.19).

Males consistently showed higher burden; in China, incidence in men aged 45–49 was 2.8-fold that of women. Key risk factors included low fiber intake, high red meat consumption, low milk intake, high BMI, and elevated fasting blood glucose, with strong co-occurrence. Decomposition analysis showed population growth and aging as main drivers, while epidemiological change varied, being positive in Brazil and negative for mortality in China.

By 2050, India and South Africa are projected to show the largest increases, China will remain high with persistent sex disparities, and Russia will be stable or declining. In clinical corroboration, overweight/obesity was an independent risk factor (aOR = 2.14, 95% CI: 1.09–4.23), and diabetes predicted worse overall survival (HR = 4.35, 95% CI: 1.59–11.93), consistent with GBD-derived metabolic patterns.</p>Conclusions<p>EOCRC burden varies across BRICS countries and will rise in most regions.

Targeted prevention focusing on dietary and metabolic risks, plus early risk-stratified screening, is urgently needed, particularly in high-risk young males. The findings could help inform or guide future prevention and screening strategies.</p>