Kidney cancer ranks 14th globally with approximately 434,419 incident cases and 155,702 deaths according to 2022 statistics. The disease shows rapidly increasing incidence and mortality with a poor prognosis, and its rates are generally higher in developed nations compared to developing ones.
Older adults aged 65 and over are particularly susceptible to kidney cancer due to mechanisms such as cellular aging, stress responses, and decreased immune function. Treatment in this population faces additional challenges including comorbidities and poor physical function status.
The main modifiable risk factors for kidney cancer include smoking, high body mass index (BMI), and occupational exposure to trichloroethylene. With the global aging population, there is an urgent need for comprehensive epidemiological studies to inform health policy decisions targeting older populations.
This study used data from the Global Burden of Disease (GBD) 2021 study, covering 204 countries and territories. Incidence, prevalence, mortality, and disability-adjusted life years (DALYs) for kidney cancer were calculated using the DisMod-MR 2.1 tool for people aged 65 years and older.
Age-standardized rates were calculated using the direct standardization method based on the world standard population from GBD 2021. Temporal trends were assessed using the annual average percentage change (AAPC) through joinpoint regression analysis with a log-linear model.
Future burden projections from 2022 to 2040 were generated using the Bayesian age-period-cohort (BAPC) model, which employs the Integrated Nested Laplacian Approximation (INLA) method. Risk factor analysis followed the GBD comparative risk assessment framework across six standardized steps.
Global incident cases of kidney cancer in adults aged 65 and older increased from 70,003 in 1990 to 203,022 in 2021, a 190% increase. The age-standardized incidence rate (ASIR) rose from 21.73 to 26.74 per 100,000, with an AAPC of 0.67%.
DALYs increased from 779,889 in 1990 to 1,826,969 in 2021, while the age-standardized DALYs rate (ASDR) went from 239.95 to 240.05 per 100,000, remaining essentially stable. Prevalence and mortality also showed significant increases of 239.25% and 150.50% respectively.
Joinpoint regression analysis revealed that the ASIR increased from 1990 to 2015 but then showed a decline from 2015 to 2021 with an annual percentage change of -0.61%. Similar turning points were observed for mortality and DALYs rates.
Males consistently exhibited higher disease burden than females across all age subgroups. In 2021, males had 1.69 times more incident cases than females (127,486 vs. 75,536). The ASIR in males increased from 29.40 to 37.68 per 100,000 compared to 16.23 to 18.00 in females.
Incident cases tripled or more in every age subgroup between 1990 and 2021, with the most dramatic increases in those aged 85 and over (more than four-fold increase). The ASIR increased significantly in all age subgroups, especially in the 95-plus group.
For males, both prevalence and mortality showed upward trends, while females experienced increases in prevalence but decreases in mortality rate and DALYs rate. This sex difference remained consistent regardless of changes in age and socio-demographic index.
The ASIR increased in all 21 GBD regions from 1990 to 2021, with East Asia showing the fastest increase (AAPC = 2.18%). High-income North America had the highest ASIR in 2021 at 66.00 per 100,000, while Oceania had the lowest at 3.18 per 100,000.
At the national level, Czechia exhibited the highest ASIR (92.25 per 100,000) and ASDR (819.88 per 100,000) in 2021. The highest AAPC increases were observed in Cabo Verde across all metrics, while Sri Lanka showed the most significant decreases.
Countries with higher socio-demographic index (SDI) levels showed a greater disease burden. The ASIR, ASDR, and SDI were positively correlated at both global and regional levels, with correlation coefficients of 0.81 and 0.70 respectively.
Smoking and high BMI were the primary risk factors for kidney cancer-related DALYs and mortality, while trichloroethylene exposure contributed minimally. In 2021, the ASDR for KC was 25.85 per 100,000 due to smoking and 48.98 per 100,000 due to high BMI.
From 1990 to 2021, the ASDR attributed to high BMI increased (AAPC = 0.66%) and trichloroethylene exposure rose (AAPC = 1.73%), whereas smoking-attributed ASDR showed a downward trend (AAPC = -0.69%). Countries with high SDI experienced the most rapid decline in smoking-attributed burden.
High BMI contributed to an upward trend in age-standardized mortality (AAPC = 0.80%), while smoking contributed to a downward trend (AAPC = -0.56%). These patterns underscore the growing importance of obesity prevention alongside continued tobacco control efforts.
Using the Bayesian age-period-cohort model, the global burden of kidney cancer among those aged 65 and older is projected to continue declining from 2022 to 2040 for both males and females.
The ASIR, ASPR, ASMR, and ASDR are estimated to fall to 22.52, 82.52, 11.81, and 192.15 per 100,000 people by 2040 respectively. The decline in males is projected to be greater than in females.
This favorable trend is attributed to heightened health consciousness, enhanced lifestyle practices, and advances in medical diagnostic technology enabling earlier detection. Early diagnosis improves the possibility of timely intervention, which helps reduce mortality.
The positive correlation between SDI and kidney cancer burden reflects how developed countries face higher rates due to greater prevalence of risk factors like smoking, obesity, and physical inactivity, as well as increased incidental diagnosis through cross-sectional imaging.
The study found notable deviations from expected SDI-based patterns: High-income Asia Pacific showed lower-than-expected ASIR, while Southern Latin America exhibited higher-than-expected ASDR relative to their SDI levels. Population aging and improved diagnostic capabilities partly explain these disparities.
The study acknowledges limitations including insufficient data from low-income countries, variations in health information systems across regions, potential underreporting in countries lacking comprehensive cancer registries, and a typical 3-year delay in GBD data collection.
The study recommends a multi-faceted approach to address kidney cancer disparities, including improving healthcare infrastructure in low-SDI regions and optimizing resource allocation in high-SDI regions. Males and older adults should be prioritized for targeted clinical guidelines.
Governments should implement national obesity prevention programs, expand tobacco control interventions including tax increases and mass media campaigns, and promote regular screening for early detection. Long-term planning is needed to sustain the projected decline through 2040.
Future research should explore molecular mechanisms underlying gender disparities, evaluate emerging diagnostic technologies in low-SDI settings, investigate environmental risk factors in industrializing regions, and conduct longitudinal studies on lifestyle intervention outcomes.
The global ASIR of kidney cancer in adults aged 65 and older increased from 1990 to 2021, while the ASDR remained stable. The burden is higher in countries with high SDI and among males, and is expected to decline through 2040.
Attributable risk factor analysis identifies smoking and high BMI as the leading contributors to kidney cancer-related DALYs and mortality among older adults. The management of these modifiable risk factors is critical for reducing future disease burden.
As population aging accelerates worldwide, it is essential to implement urgent response strategies focusing on older populations, rationalize health resource allocation, and provide targeted clinical guidelines to address the growing burden of kidney cancer.