Comparative analysis of female breast cancer burden in China along the global sociodemographic gradient: risk attribution, decomposition, and age-period-cohort evidence from GBD 2021

Objective To assess temporal changes in female breast cancer burden in China from 1990 to 2021, its global and Socio-Demographic Index (SDI) status, attributable risks, death drivers and age-period-cohort (APC) features based on GBD 2021 data.Methods We extracted data on incidence, deaths, DALYs and seven attributable risks for China, the world and five SDI regions. Estimated Annual Percentage Change (EAPC) analyzed age-standardized rate trends. Shapley decomposition divided attributable death changes into population growth, aging, age-specific mortality and Population Attributable Fraction (PAF). APC models estimated temporal drifts.Results From 1990 to 2021, the Age-Standardized Incidence Rate (ASIR) increased from 24.54 to 29.36 per 100,000 (EAPC = 0.30%, 95% CI: 0.20 to 0.41%) in China, whereas the Age-Standardized Mortality Rate (ASMR) decreased from 10.65 to 6.46 per 100,000 (EAPC = -2.02%, 95% CI -2.20 to -1.85%). By 2021, both rates were lower in China than in the global population and all five SDI regions. The leading PAFs for Disability-Adjusted Life-Years (DALYs) burden were high red meat intake, secondhand smoke, high fasting plasma glucose, high body mass index, and low physical activity. Decomposition showed that increasing risk-specific attributable deaths were mainly driven by population growth and ageing, while declining age-specific mortality contributed negatively. Incidence net drift was 0.232%/year; mortality net drift was -2.115%/year.Conclusion China showed a transitional breast cancer burden pattern, characterized by slowly rising incidence, declining age-standardized mortality, and a shift toward metabolic risk contribution. Population ageing and metabolic risk accumulation may continue to increase the absolute burden despite improvements in mortality risk.