Global, regional, and national burden of bladder cancer from 1990 to 2021 with projections to 2050: insights from the global burden of disease study and Mendelian randomization analysis.

BACKGROUND

Bladder cancer remains a global health challenge with marked demographic and regional disparities. Understanding long-term trends, risk factors, and projections is essential for effective prevention.

METHODS

Data on bladder cancer were extracted from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021. We focused on the effects of age, sex, risk factors, and the socio-demographic index (SDI) on the burden of bladder cancer and calculated the average annual percent change (AAPC) via joinpoint regression. Mendelian randomization (MR) to assess causal risk factors, and Bayesian age-period-cohort (BAPC) models to forecast future burden.

RESULTS

From 1990 to 2021, the global age-standardized incidence rate slightly declined (AAPC = - 0.269), prevalence increased (AAPC = 0.145), and both mortality (AAPC = - 0.840) and DALYs (AAPC = - 1.022) decreased significantly. The burden was significantly higher among males and older adults and showed substantial variation across SDI regions. Smoking and high fasting plasma glucose were strongly associated with bladder cancer DALYs, accounting for 27.8% and 7.4%, respectively. MR studies have confirmed that smoking and testosterone levels can increase the risk of bladder cancer. The prediction results indicate that the global age-standardized incidence rate will moderately decrease from 2022 to 2050.

CONCLUSION

Despite a gradual decline in mortality and incidence, bladder cancer continues to impose a substantial health burden, particularly among males and in high-SDI regions. Smoking and high fasting glucose are key modifiable risk factors. Sustained prevention and resource allocation are essential to mitigate the rising absolute burden in aging populations.