This study is a retrospective cross-sectional analysis based on GBD 2021, aimed at exploring the differences in and trends of GC incidence, mortality, and DALYs in the Western Pacific region from 1990 to 2021. Additionally, the BAPC model was used to predict ASRs for selected countries, extending to 2040. The data utilized in this study are publicly available and do not involve personal privacy or sensitive information. The original study received ethical approval; therefore, no additional ethical clearance is required for this research.

In May 2024, the GBD project released its 2021 dataset, provided by the Institute for Health Metrics and Evaluation (16). Covering the period from 1990 to 2021, the dataset includes epidemiological assessments of 371 diseases and 88 risk factors across 204 countries and territories. It evaluates metrics such as incidence, prevalence, mortality, years lived with disability, years of life lost, and disability-adjusted life years (15, 17). Data sources include death registries, verbal autopsies, censuses, household surveys, disease registries, and healthcare utilization records (15, 17). The data is available at https://vizhub.healthdata.org/gbd-results/, with additional source information at https://ghdx.healthdata.org/gbd-2021/sources. Diseases are defined using International Classification of Diseases codes, and modeling tools like DisMod-MR and spatiotemporal Gaussian process regression are used for estimating cancer burden (15, 17, 18). The data process includes adjustments for heterogeneity and bias, with uncertainty analyzed through Monte Carlo simulation (15, 17). More details on the models can be found at https://www.healthdata.org/gbd/methods-appendices-2021/cancers.

The World Health Organization (WHO) divides the world into six regions: Africa, the Americas, Eastern Mediterranean, Europe, South-East Asia, and the Western Pacific (19). This study focuses on 31 countries and regions within the Western Pacific (hereafter referred to as countries) and compares them to global data (20). The 31 countries included are: Papua New Guinea, Solomon Islands, Vanuatu, Cambodia, Laos, Kiribati, Marshall Islands, Tuvalu, Micronesia, Samoa, Mongolia, Nauru, Tonga, Vietnam, the Philippines, Fiji, Tokelau, China, American Samoa, Niue, Malaysia, Palau, Northern Mariana Islands, Cook Islands, Guam, Brunei, Australia, New Zealand, Singapore, Japan, and South Korea. The study primarily analyzed the trends in GC incidence, mortality, and DALYs for these countries between 1990 and 2021.

In 2021, the Western Pacific region reported 1,230,232.61 (95% UI: 1,052,350.05–1,409,969.66) new GC cases, accounting for 61.48% of the global total and ranking highest among WHO regions ( Table 1 ). From 1990 to 2021, incident cases increased by 37.12%, surpassing the global average, while the improvement in incidence rates was second only to Europe ( Table 1 ). The ASIR in 2021 was 26.76 (95% UI: 21.71–32.33) per 100,000 population, the highest globally, yet the region’s ASIR improvement from 1990 to 2021 exceeded the global average, second only to Europe ( Table 1 ).

In 2021, GC deaths in the Western Pacific region reached 533,973.62 (95% UI: 431,189.38–647,568.07), accounting for 55.95% of the global total, the highest among WHO regions ( Supplementary Table 1 ). Since 1990, deaths have risen faster than the global trend, yet the region’s improvement ranks second only to Europe ( Supplementary Table 1 ). The ASMR in 2021 was 18.94 (95% UI: 15.30–22.87) per 100,000 population, the highest among WHO regions and well above the global average ( Supplementary Table 1 ). Despite this, ASMR has declined significantly since 1990, with progress outpacing the global rate, second only to Europe ( Supplementary Table 1 ).

In 2021, GC accounted for 12,332,045.27 (95% UI: 9,929,295.78–15,227,868.18) DALYs, making up 54.12% of the global total and the highest among WHO regions ( Supplementary Table 2 ). From 1990 to 2021, DALYs declined by 4.76%, with improvements surpassing the global average, second only to Europe. The 2021 ASDR was 437.57 (95% UI: 352.93–539.40) per 100,000 population, the highest among WHO regions and well above the global average ( Supplementary Table 2 ). Since 1990, ASDR has declined, with progress outpacing global trends, second only to Europe ( Supplementary Table 2 ).

In 2021, the countries and territories in the Western Pacific with the highest number of incident cases were China, Japan, and South Korea, with China reporting the highest number at 611,798.97 (95% UI: 471,965.81–765,562.25), accounting for 80.89% of the total cases in the region ( Table 2 ; Figure 1 ). From 1990 to 2021, only Tokelau (-25.74%), Niue (-22.57%), and Japan (-8.54%) showed a declining trend in incident cases, while most other countries and territories experienced an increase, with Malaysia seeing the largest growth at 134.26% ( Table 2 ; Figure 1 ). In 2021, China and Mongolia had an ASIR above the regional average, with Mongolia recording the highest ASIR at 36.83 cases per 100,000 population, while the Philippines had the lowest at 4.48 (95% UI: 3.72–5.94) per 100,000 population ( Table 2 ; Figure 1 ). Notably, from 1990 to 2021, the ASIR declined in all countries and territories within the Western Pacific, with South Korea experiencing the most significant decrease, having an AAPC of -3.23 (95% CI: -3.47 to -2.98), whereas Kiribati had the smallest decline, with an AAPC of -0.34 (95% CI: -0.38 to -0.29) ( Table 2 ; Figure 1 ).

In 2021, the Western Pacific countries and territories with the highest number of GC deaths were China, Japan, and South Korea, with China recording the highest death toll at 445,012.65 (95% UI: 344,736.20–555,833.96) ( Supplementary Table 3 , Supplementary Figure 1 ). From 1990 to 2021, only four countries and territories in the region saw a decline in GC deaths: Nauru (-2.36%), Niue (-24.54%), South Korea (-28.83%), and Tokelau (-29.48%), while most others experienced an increase, with the Philippines showing the largest rise at 118.50% ( Supplementary Table 3 , Supplementary Figure 1 ). In 2021, Mongolia had the highest ASMR for GC in the region at 37.40 (95% UI: 29.36–45.86) per 100,000 population, while Australia had the lowest at 3.78 (95% UI: 3.34–4.12) per 100,000 population ( Supplementary Table 3 , Supplementary Figure 1 ). Notably, from 1990 to 2021, ASMR declined across all countries and territories in the Western Pacific, with South Korea experiencing the most significant decrease, with an AAPC of -4.53 (95% CI: -4.81 to -4.24), while Kiribati had the smallest decline, with an AAPC of -0.38 (95% CI: -0.42 to -0.33) ( Supplementary Table 3 , Supplementary Figure 1 ).

In 2021, the countries and territories with the highest DALYs due to GC in the Western Pacific region were China, Japan, and South Korea, with China ranking first at 10,642,126.54 (95% UI: 8,222,106.35–13,383,779.05) DALYs ( Supplementary Table 4 , Supplementary Figure 2 ). From 1990 to 2021, approximately one-third of the countries and territories in this area experienced a decline in DALYs, with South Korea showing the most significant reduction at -46.83%, while Vanuatu recorded the highest increase at 112.55% ( Supplementary Table 4 , Supplementary Figure 2 ). Regarding ASDR, Mongolia had the highest ASDR in the region in 2021, reaching 930.45 (95% UI: 747.52–1157.92) DALYs per 100,000 people ( Supplementary Table 4 , Supplementary Figure 2 ). Notably, from 1990 to 2021, all countries and territories in the Western Pacific saw a downward trend in ASDR, with South Korea experiencing the largest decrease, as reflected by its AAPC of -5.06 (95% CI: -5.32 to -4.79), whereas Kiribati had the smallest decline, with an AAPC of -0.47 (95% CI: -0.52 to -0.42) ( Supplementary Table 4 , Supplementary Figure 2 ).

Since 1990, the number of incident cases in the Western Pacific region has continued to rise, with China and the Philippines showing an upward trend, while Japan experienced an accelerated decline after 2011, whereas Singapore and Vietnam saw rapid increases starting in 2015 and 2010, respectively ( Figure 2 ). In China, the trends of death cases and DALYs showed similar fluctuations ( Supplementary Figures 3 , 4 ). In contrast, Japan’s number of deaths remained relatively stable from 1990 to 2021, though DALYs showed a steady decline ( Supplementary Figures 3 , 4 ). The Philippines experienced a steady increase in both death cases and DALYs, whereas Singapore saw a sharp rise in both indicators from 2015 onward ( Supplementary Figures 3 , 4 ). Similarly, Vietnam also displayed an accelerating growth trend after 2010 ( Supplementary Figures 3 , 4 ).

From 1990 to 2021, the ASIR, ASMR, and ASDR of GC in the Western Pacific region and its representative countries showed an overall declining trend ( Supplementary Figures 5 – 7 ). The ASIR, ASMR, and ASDR for males were consistently higher than those for females, with both sexes exhibiting similar trends of change ( Supplementary Figures 5 – 7 ). The Western Pacific region and China experienced a slight peak around 2005, followed by an overall decline ( Supplementary Figures 5 – 7 ). Japan demonstrated a relatively stable downward trend, while Singapore showed a steady decline from 1990 to 2015, followed by a fluctuation of increase and then decrease after 2015 ( Supplementary Figures 5 – 7 ). Malaysia exhibited a more fluctuating downward trend ( Supplementary Figures 5 – 7 ). Vietnam displayed an overall decline, with an accelerated decrease after 1995 and a slight slowdown around 2010. Similarly, the Philippines showed an overall downward trend, with a noticeable acceleration in the decline after 2005 ( Supplementary Figures 5 – 7 ).

In this study, the population of the Western Pacific region was divided into 20 age groups, each spanning 5 years ( Figure 3 ). The findings revealed that in most age groups, the number of incident cases, number of deaths, DALYs, and ASRs of GC were consistently higher in males than in females ( Figure 3 ). The number of incident cases, number of deaths, and DALYs for both sexes, as well as for males and females separately, exhibited an overall trend of initial increase followed by a decline, with the turning point occurring between the ages of 65 and 74 ( Figures 3A, C, E ). Regarding ASRs, males had the highest rates, followed by the overall population, with females showing the lowest rates ( Figures 3B, D, F ). Among males, the ASRs increased initially and then decreased, with a turning point in the 90-94 age group ( Figures 3B, D, F ). In contrast, females exhibited a generally continuous increase in the ASRs with advancing age ( Figures 3B, D, F ).

From 1990 to 2021, the gap in the overall incidence, mortality, and DALYs rates of GC between countries with the highest and lowest SDI narrowed. Specifically, the Slope SII for incidence decreased from 14.45 to 10.97 ( Figure 4A ), for mortality from 12.89 to 8.51 ( Supplementary Figure 8A ), and for DALYs rate from 265.69 to 134.13 ( Supplementary Figure 9A ).

However, in contrast, the relative gradient of inequality, as measured by the Concentration Index, exhibited a different trend. In 1990, the Concentration Index for incidence, mortality, and DALYs rates was -0.15, -0.09, and -0.05, respectively ( Figure 4B ; Supplementary Figures 8B , 9B ). By 2021, these values had changed to -0.203, -0.154, and -0.108, indicating an increase in the relative degree of inequality ( Figure 4B ; Supplementary Figures 8B , 9B ).

The study selected representative countries for forecasting ASRs through 2040. Japan and Singapore were chosen to represent high-income countries, China and Malaysia to represent upper-middle-income countries, and Vietnam and the Philippines to represent lower-middle-income countries. The ASIR, ASMR, and ASDR for GC in these six countries were predicted using the BAPC model. The projections indicate an upward trend for all indicators except for the ASDR in Malaysia, which is expected to decrease by 2040 ( Figure 5 ; Supplementary Figures 9 , 10 ).