Discussion

In this study, we comprehensively described the global burden and epidemiological trends of CNS tumors among children and adolescents over the past 32 years. Overall, a global decline was observed, particularly in mortality and disability‐adjusted life years (DALYs). Regionally, high and high‐middle SDI areas demonstrated continuous improvement, whereas low and low‐middle SDI countries experienced an increasingly dire situation in recent years. Among all age groups, the youngest cohort (0–4 years) faced the highest overall risk but showed the most pronounced declines in both incidence and mortality. In contrast, older groups (10–19 years) exhibited either a mild increase in incidence or only modest reductions in mortality.

The higher incidence observed in high‐SDI regions should be interpreted with caution, as this pattern is critical to understanding global disparities. Differences in diagnostic intensity, including greater availability and utilization of neuroimaging, more comprehensive cancer registry coverage, and more standardized coding practices, are likely to contribute to higher case ascertainment in these settings. Consequently, incidence estimates may partly reflect differences in detection capacity rather than true underlying risk. In contrast, underdiagnosis and incomplete reporting in low‐SDI regions may lead to underestimation of the actual disease burden. These methodological considerations are therefore critical for properly contextualizing regional disparities and should be carefully accounted for when interpreting SDI‐related patterns.

At the country level, considerable variation was observed across SDI categories (Tables S9 and 10). Many high and high‐middle SDI countries, such as the United Kingdom and Iceland, as well as Italy and China, showed decreases in both ASIR and ASDR. Conversely, several countries—including Monaco, Japan, and Belarus—displayed increases in both ASIR and ASDR. These disparities mirror the persistent inequalities in economic development and healthcare resource distribution worldwide. In particular, when access to medical resources becomes a limiting factor, countries with higher population densities may experience greater pressure from mortality burdens.

Notably, patterns observed in children and adolescents may differ from those reported in all‐age populations [25]. Previous global assessments have suggested that, in the general population, the burden of CNS tumors is strongly influenced by aging and diagnostic capacity, whereas pediatric cases are more closely related to developmental and biological factors. While direct comparisons are limited by differences in age structure and disease composition, the relatively distinct trends observed in younger populations highlight the importance of age‐specific analyses. These differences underscore the need to interpret pediatric CNS tumor burden independently from all‐age estimates.

To further examine differences in burden trends, two sets of countries were analyzed in greater detail. The first group, China and India, represents nations with large populations, while the second group, Japan and Norway, includes economically and medically advanced countries since the 1990s (Figure 5, Table S8). In China, ASIR displayed a cyclical pattern over roughly 15‐year intervals: an initial decline from 1990 to 2005, followed by an upward phase through the next 15 years, and an apparent decrease beginning around 2020. India showed a similar pattern, with a mild decline during the early 2000s and a gradual increase thereafter (Figure 5A). Both countries exhibited comparable ASDR trends. Since 1990, China's ASDR has dropped by more than half—from 2.23 (95% UI: 1.51–2.75) to 1.08 (0.81–1.45) in 2021—while India has achieved a steady 20% reduction over the same period (Figure 5B).

Figure 5: Comparison of ASIR and ASDR trends between different countries from 1990 to 2021. (A) ASIR of China and India from 1990 to 2021; (B) ASDR of China and India from 1990 to 2021; (C) ASIR of Japan and Norway from 1990 to 2021; (D) ASDR of Japan and Norway from 1990 to 2021. ASDR, age‐standardized death rate; ASIR, age‐standardized incidence rate.

In Japan, ASIR decreased slightly for about 15 years before rising sharply to 2.95 (95% UI: 2.47–3.41) in 2021. ASDR remained relatively stable around 0.50 for nearly two decades but increased by nearly 20% to 0.58 (0.55–0.61) by 2021. In contrast, Norway showed a fluctuating yet overall declining trend in both morbidity and mortality, suggesting progressive improvements in disease burden (Figure 5C,D).

Among the selected countries, both China and India showed rising ASIR and ASDR, likely linked to their rapid economic growth, substantial improvements in healthcare systems, advancements in medical research, and expanding international collaboration. In contrast, despite Japan's well‐developed economy and healthcare infrastructure, both ASIR and ASDR have worsened. Several hypotheses may help to explain these trends, including changes in diagnostic practices and increased detection associated with wider availability of neuroimaging, as well as potential shifts in environmental exposures or population‐level risk factors. In addition, improvements in case ascertainment and reporting completeness over time may also contribute to the observed increases. These factors warrant further investigation to better understand the drivers of disease burden in this setting.

The apparent increase in CNS tumor detection in low and low‐middle SDI countries may partly reflect better diagnostic capabilities, which does not necessarily reflect a true increase in disease burden. However, the rising mortality burden in recent decades is of greater concern. Globally, the increased ASIR observed in low, low‐middle, and high SDI countries might be associated with environmental factors, such as excessive early exposure to electronic devices, environmentally induced genetic alterations, pollution, and ionizing radiation [15, 26]. The countertrend observed between ASDR and ASIR may largely reflect improved access to primary health care, enhanced medical coverage, and progress in surgical techniques, high‐quality nursing [27], and multidisciplinary treatment. For instance, the wide application of imaging technology not only enhances the diagnostic rate but also makes early intervention feasible.

In countries with persistently high or rising mortality, priorities should include advancing surgical techniques, adopting standardized and effective treatment protocols, improving postoperative management, preventing complications, and increasing medical investment—especially in resource‐limited regions. These measures are crucial to mitigating mortality.

Driven by improved medical standards, major advances in basic research, extensive drug development, clinical trials, and continuous progress in surgery and postoperative care, numerous breakthroughs in CNS tumor management have markedly prolonged survival among affected patients [28, 29, 30, 31, 32]. Moreover, emerging technologies and discoveries are transforming the understanding of CNS tumors and providing a foundation for more effective therapies [33, 34, 35, 36].

Looking ahead, efforts should focus on strengthening health systems rather than pursuing population‐level screening strategies unsupported by current evidence. Improving diagnostic capacity, streamlining referral pathways, and expanding access to specialized pediatric neuro‐oncology services remain central to achieving timely diagnosis of CNS tumors in children. In economically underdeveloped regions, greater investment in radiotherapy infrastructure, multidisciplinary care, and supportive services is particularly needed to address persistent disparities in outcomes. In addition, previous studies have also suggested possible associations between CNS tumor incidence and factors such as electronic device use, radiofrequency electromagnetic radiation, and environmental exposures [26, 37]. Although these cannot be interpreted as causal based on Global Burden of Disease analyses, they may be more appropriately viewed as hypotheses that merit further investigation to clarify the underlying etiological mechanisms.

In light of these findings, while continued exploration of CNS tumor etiology remains essential, future health policies should prioritize reducing mortality and minimizing fatal or disabling treatment complications. Ongoing industrialization, particulate pollution, and electromagnetic exposure may further increase the incidence of CNS tumors, particularly in low and low‐middle SDI regions [38]. Addressing both morbidity and mortality simultaneously is key to effectively lowering the global burden of CNS tumors and advancing progress toward the 2030 Sustainable Development Goals [39].

There are several limitations in the study. The analysis described the burden and temporal trends of CNS tumors but did not address etiology or environmental risk factors, as the Global Burden of Disease framework does not yet attribute these to brain tumors in a standardized way. The underlying data also carry inherent uncertainty. Because the estimates draw on heterogeneous sources, differences in extraction methods and in the reliability of the original studies are unavoidable; these are compounded by the different diagnostic and reporting standards adopted across countries and institutions, so that the reported figures may vary considerably across regions. A portion of the observed variation in incidence and mortality is likely to arise from changes in diagnostic and screening infrastructure, particularly the broader availability of neuroimaging, rather than from genuine shifts in disease risk; this concern is most salient where diagnostic capacity has expanded rapidly.