Global Burden, Trends, and Inequalities of Gallbladder and Biliary Tract Cancer, 1990-2021: A Decomposition and Age-Period-Cohort Analysis.

Background: Gallbladder and biliary tract cancer (GBTC) increasingly aggravates the global malignancy burden. This study aimed to evaluate the updated condition of GBTC temporal burden trends and inequalities from 1990 to 2021.

Methods: Data on GBTC were extracted from the Global Burden of Disease (GBD) 2021 study. Incidence, deaths, and disability-adjusted life years (DALYs) and their age-standardised rates (ASR) were quantified from 1990 to 2021, stratified by sex, age and sociodemographic index (SDI). The age-period-cohort (APC) model was used to elucidate the effects of age, period, and cohort. Decomposition analysis and cross-country inequality evaluation were performed to assess the contributing factors and disease imbalance, respectively. Bayesian APC analysis was used to estimate the future burden.

Results: In 2021, the global incident cases of GBTC were 216 768, with 171 961 deaths and 3 732 121 DALYs lost. From 1990 to 2021, the ASR of incidence, mortality, and DALYs decreased slightly. Males showed a slight increase in ASR of incidence, while females experienced a significant decrease. High-income regions, particularly in Asia Pacific and Latin America, exhibited a higher burden, while Western Sub-Saharan Africa had the lowest. Low and low-middle SDI regions showed a gradual rise in all metrics despite lower absolute numbers. The APC analysis indicated that the global incidence of GBTC tended to rise with age, but gender differences existed. Besides, a deteriorating cohort effect was detected amongst individuals born between 1907 and 1917. Decomposition analysis revealed that population growth was the primary driver of the increased GBTC burden globally. Significant disparities in GBTC burden by SDI were observed, with a notable decline in inequality over time. Projections indicated a slow decline in the global ASR through 2040, with a more pronounced decrease in females.

Conclusions: There are significant regional and gender differences in the global burden of GBTC. Population growth remains a major contributor to the burden. Despite the overall decline, the increasing incidence in low and lower-middle SDI regions and the persistent male burden highlight the need for targeted interventions. Future efforts should focus on addressing socio-economic inequalities and reducing risk factors, particularly in vulnerable populations.